As the main translator of Murasaki (I translated everything except a couple of the graphics), I have a fairly solid understanding of everything in the game (in terms of both gameplay and story), so I thought I'd write this guide to help people out. The first section is an overview of the main game mechanics (feel free to skip this and dive right into the game - like many of Tetsu's games, Murasaki is fairly intuitive), the second and third give some gameplay advice, and the fourth is for people who want a better understanding of the storyline. I may add to this later if people have more questions, or if I think of anything important I've forgotten.

- Falcarius

Perhaps the best way to describe Murasaki's gameplay would be "Touhou meets Irisu Syndrome". Like the Touhou series, Murasaki is a bullet hell game in which you shoot enemies, collect score items, and dodge loads and loads of bullets. The game is divided into stages, each of which consists of many weak enemies followed by a much stronger boss. The boss will change its attack pattern each time you deal enough damage or spend too long trying to do so, and once it runs out of attack patterns, you have beaten that stage... assuming you can survive that long. Fortunately, there are a couple of ways in which Murasaki is kinder than the Touhou games - firstly, you have a health bar instead of dying from a single hit, and secondly, you play one stage at a time instead of having to clear them all in one go.

However, another major difference from Touhou is that you can only fire one bullet at a time (or to put it more accurately, you can only have one bullet on screen at a time), so clearing out vast waves of enemies/bullets just by shooting them quickly becomes impractical. This is where the Irisu Syndrome part comes in. Over time, coloured shapes gradually appear on the field, and like pretty much everything else, touching them will hurt you. However, if you shoot them, they will bounce around like billiard balls for a second or two before exploding, and if they collided with any matching shapes in that time, those shapes will also explode. These explosions don't damage you, but they do cause damage to enemies/bullets. So basically, the idea is to knock the blocks into each other and create large explosions that clear up the screen for you.

If you're in serious trouble, you can use a "special attack" or "bomb" by holding down the special attack key (X by default) for about a second, then releasing it. You can't launch special attacks instantly like in Touhou (so no "death-bombing"), but you can charge them up for a longer time to make the attack more powerful. The number of special attacks you have remaining is shown by the red circle icons at the bottom left of the screen, and you can earn more by collecting red powerups (dropped by red-tinted enemies). Similarly, blue-tinted enemies drop blue powerups that restore some of your health (shown by the yellow bar on the left). Most enemies/bullets will drop purple circles when destroyed, which you can collect to increase your score (the number at the far left). Note that not all enemies or bullets can be destroyed with a single hit, and a few can't (or shouldn't) be destroyed at all.

Bosses work slightly differently - in addition to causing explosions near them or just shooting them in the face, you can also damage them indirectly by causing explosions near their bullets. Any bullets destroyed by an explosion during a boss battle will turn into red arrows that fly towards the boss, injuring them. Once you make it to a certain point in the boss battle, as long as you haven't bombed or waited out too many of their attack patterns, they will drop a splotchy red "powerup". Collecting this will cause the boss to use a special attack pattern, so if you're running low on health, you should probably just avoid it. You don't need to trigger any special attacks to complete the stage, although they are important for completing your Collection.

Speaking of which, completing certain tasks or challenges will unlock entries in the Collection, ranging from background music to story segments and character profiles. Completing the Collection will unlock a secret ending, although it's not critical to the game's story. There are also two extra modes that you can unlock by completing the main story: Unprotected Mode (or "Hard Mode") and Dream Mode (or "Endless Mode"), which you can access by pressing up or down on the stage select menu. Playing Dream Mode will unlock a couple more items in the Collection, while Unprotected Mode is just there for the challenge.

• Just like in Touhou, your actual hitbox is a lot smaller than your sprite, so bullets can pass right through your head or feet without damaging you. It's hard to tell exactly how big the hitbox is, but it seems to be a few pixels at about waist/torso height.
  
• You don't actually need to touch the powerups to collect them - if you get close enough, the powerup will automatically move towards you after a second or two.
  
• You can automatically collect all score items on screen by bumping into either edge of the game screen.
  
• Chaining together more blocks will create larger explosions and earn you more points. Try to survive without shooting for as long as you can, so that more blocks can appear on screen.
  
• Kairi's bullets will reflect off the top of the screen, allowing you to hit objects below you as well as above (and don't worry, your own bullets don't hurt you).
  
• Satsuki's bullets only travel a short distance, but they will still reflect off the top of the screen if you're close enough. The short-lived bullets also allow you to shoot more quickly, and will knock blocks further.
  
• If you're having trouble on Stage 2 (specifically Ayame's bullet spam at the start), feel free to use your special attacks, at least until you figure out a strategy to dodge the attacks.
  
• If you can't get the boss to appear on Stage 4, you have to destroy the flowers in the corners without destroying the main cocoon. If you just wait it out, the boss won't appear, but you will get some hard-to-read text just above the cocoon.
  
• If you can't get the boss to fight you normally on Stage 5, have a look through the Collection/achievement requirements for a hint. You need to wait out the midbosses - if you kill any of them, you get the bad end.
  
• Once you've unlocked both parts of a character's profile in the Collection, you can press the confirm key (Z by default) on either part to see some extra information about that character.

• Pressing the pause key (Esc by default) on the main menu screen will bring up a list of all rounds you have played, and you can select any round to watch a replay of it. Watching replays is a good way to learn enemy attack patterns and figure out strategies to improve. You can press the confirm key (Z by default) during a replay to fast-forward, although there's no rewind option.
  
• You can also access replays by pressing the confirm key on the Score menu, although this only gives you the five highest-scoring runs per character per stage.
  
• Pressing the pause key on the Collection screen will allow you to see the unlock conditions for items that you have already unlocked.
  
• You don't actually need to unlock every item in the Collection to see the special ending - you only need 48. However, duels and music don't count, and Dream Mode unlocks are only worth half as much. In other words, if you unlock all Dream Mode items, you can be missing four normal items and still unlock the special ending (good news for anyone struggling with Stage 6). On the other hand, if you never play Dream Mode, you'll need to unlock every normal Collection item (including the Stage 6 ones) to get the special ending.
  
• For anyone who's used to Touhou mechanics: using a bomb does not make you invincible. You are never invincible in Murasaki, not even while enemies are talking.
  
• Causing damage to a boss while they're talking will cause them to end the conversation immediately and begin their next attack. If you want to see all the conversations, don't shoot while the bosses are talking.
  
• Completing all Duels in a stage will cause a picture of the boss to appear at the end of the stage. There's also a different picture for Stage 5 if you don't complete all Duels. If you manage to complete all Duels and still have 70% or more health remaining at the end of the stage, you will also unlock an extra bit of dialogue from the boss just before they explode. Winning with more than 70% health will also get you a special ending picture on Stages 5 and 6.
  
• If you are near the edge of the screen towards the end of Stage 3, you may see the other player character appear. Bump into the wall to have a brief conversation with them (the conversation changes if your remaining health is above 70%).
  
• Your best times for Duels are recorded in the Collection. If you bombed or took any damage, the time will be listed under "Good", otherwise it will be listed under "Great". You don't unlock anything for getting "Great" completion times, though.
  
• To get high scores, try to wait until a lot of bullets are on screen before setting off a large explosion, then use the wall-bump technique to make sure you've collected all the score. Satsuki tends to earn more points than Kairi because of her larger explosions. You can get quite a lot of points from bosses, particularly if you defeat them quickly and without bombing. Make sure to complete all Duels (another reason to avoid bombing or timing out attacks). You also get bonus points for your remaining health at the end of the stage, so try not to take too much damage. Stage 2 is particularly difficult to get the score achievement for, but don't give up!
  
• When trying to clear Stages 1 to 5 in order, dying will reset your progress, but pausing and quitting won't. If you're unsure about your progress, check the Collection - a set of asterisks will be displayed next to the unlock conditions, showing how many stages you've cleared.
  
• If you're having trouble with Stage 6, I can't help you. Just practise a lot and watch other people's replays, and hopefully you'll improve. Luckily, Rinko only recovers her health once, and she gives you a health powerup while she's at it.

Q: What's with the dialogue in Stage 1? It makes no sense.
A: Complete all the Stage 1 Duels with both Kairi and Satsuki to unlock Kano's full profile in the Collection. After reading both parts of her profile, play Stage 1 again (or watch a replay of it), paying attention to the pitch of the "text appearing" sound effect. Kano consists of a girl and a sentient flower who are now permanently attached. The dialogue in Stage 1 is a conversation between the girl and the flower. As for which dialogue belongs to which speaker... that's up to your interpretation ;)

Q: If Haiga was such a great warrior, why is he only a Stage 2 boss?
A: Complete all the Stage 2 Duels with both Kairi and Satsuki to unlock Haiga's full profile, and survive the attack at the beginning of Stage 2 without bombing or taking any damage to unlock Ayame's profile. Read them both, then take a close look at Haiga's sprite (and the end-of-stage picture, if you can get a long enough look at it). Also pay attention to his health bar. Haiga has just survived an actual battle against Ayame, who probably insta-killed you a few times at the start of Stage 2 without even trying. He didn't come out of it too well, though - he lost a wing and his sword arm, and is probably bleeding out while he's fighting against you - but he still manages to put up an impressive fight. Stage 6 reveals that Rinko found Haiga's sword, and several of her attacks are more difficult copies of Haiga's Stage 2 attacks.

Q: What's with all the instruments?
A: You'll need to survive all of the midbosses without bombing or taking damage (or killing the midboss, in the case of Stage 5) in order to unlock all the relevant Collection items. There are a few other relevant items too, particularly the Quartet one (destroy 1000 blocks) and the main story entries. Take a close look at the profile images after reading the Quartet entry. Three wandering musicians from different worldlets formed the Trio, and eventually met Yuna and became the Quartet. However, the three original members ended up defying the politicians of -I- and were executed to set an example. Kusagi had his ears removed, Tomato had her eye crushed, Shiho was fed poison, and the three were then hung or garrotted (note the red lines on their necks). Because of their lingering regrets, their souls remain in the form of instruments, which follow the player to Yuna's village. There, they take on human form for one last performance...

Q: There are a lot of androgynous characters in this game. What gender is [insert character here]?
A: You should be able to figure out everyone's genders from the pronouns used in their Collection profiles. I actually had to check with the author a couple of times when translating the game, so all genders are confirmed by Word of God.

Q: What's with the worldlet names?
A: There is an ancient Japanese poem called Iroha[en.wikipedia.org] which uses each syllable of the Japanese "alphabet" exactly once. Because of this, the syllables in Iroha order ("i ro ha ni ho he to...") are sometimes used as an ordering system, similar to the way we use Roman numerals. They are also used to represent musical notes, kind of like "do re mi..." in English. The symbols for the worldlets are based on the characters "i", "ro", "ha" and "ni" in different Japanese scripts. Because of all this symbolism, I wanted to leave the names as "I", "Ro", "Ha" and "Ni" when I translated the game, but they would be very confusing in English (particularly "I"), so I added the dashes on either side to make them more distinctive.

Q: What about the names of Rururu's fish?
A: Those are based on the Celestial Stems[en.wikipedia.org], a Chinese date/numbering system that the Japanese also use occasionally. The Japanese names for the first four stems are "kou", "otsu", "hei" and "tei"... which suggests that there may be a fourth fish out there somewhere.

Q: Okay, is there any more Japanese wordplay in the game?
A: The most significant one is "shiawase-gumi", which I translated as "Team Fortune". "Shiawase" means "happiness" or "good fortune", but it can also mean "combination of four". There's also the title of Haiga's background music, "Amei Sensou" ("Fruitless, Noisy War") - "amei sensou" is a Japanese phrase referring to annoying noise or pointless arguments, but the song title replaces the word "sensou" with a homophone that means "war". Finally, "murasaki" means "purple", but one of Kairi's Dream Mode items in the Collection implies that he used to know somebody named "Murasaki" (spelled with the symbols for "thicket" and "bloom").

Q: What's the white text that flashes across the screen at the start of each duel?
A: Those are the names of the duels. Here's my translations of them:
Kano: 子孫繁栄祈願 (Prayer for Prosperity of Offspring), 昇華一心 (Sublimation of One Accord)
Haiga: 冥龍星裂・翔 (Dark Dragon's Star Burst: Soaring), 皇龍咆哮・邪 (Emperor Dragon's Roar: Evil)
Rururu: 独立独歩拳 (Self-Reliance Fist), 和気藹藹拳 (Peace and Harmony Fist)
Kozuyo: 憤慨憤慨砲 (Double Resentment Cannon), 捲土重来舞 (Back with a Vengeance Dance)
Yuna: この日この場所で (On This Day, In This Place), 幾星霜月 (Many a November), 旋律迷宮 (Melody Labyrinth), 千紫万紅 (Multitude of Colours)
Rinko: 風星ノ波（改） (Waves of Wind and Stars (v2)), 舞影陣（改） (Dancing Shadow Formation (v2)), 百閃花凛 (Hundred Flash Flower Chill)