Haydee is a hidden gem. What I thought was a generic indie shooter (with the only difference that you play as a sexy robo-mommy) turned out to be a hardcore (maybe not hardcore but definitely rather difficult) puzzle platformer survival shooter.

This game reminds me of:

System Shock
* There's no map, no objectives, no tutorial, even the items in your inventory don't have a name or a description - it's up to you, the player, to figure out where to go and what to do.
* Some people may find frustrating that you can't shut off your brain while playing it, not because of the puzzles being difficult but because you'll have to keep a map of the area (at least the area which you're currently exploring) in your memory, you'll also have to remember where the locked doors are and which keys they require to open.
* There's a lot of backtracking, so you'll have to plan your route carefully if you want to minimise that.

Resident Evil
* Each savegame requires one floppy disk which you need to find first, therefore saving once after a perfect run where you looted 2-3 locations may be a better choice than saving after each location separately and wasting disks.
* There's an item box in almost each save room which gives you access to all items you collected.
* Every bullet counts, so think which enemies you should kill and which enemies you can dodge. There're some weapons apart from the default pistol but you'll need to find them first as well as find a way to actually get to them.

Portal
The overall looks of the rooms and corridors. Everything's neat and clean, the walls are white for the most part, whereas pipes, buttons, etc. are green, red, etc.

The protagonist is sexy as hell. This is what women in videogames are for - to be an eye candy. Similar to how this worked in NFS Underground / Most Wanted or Tomb Rader, which are great games even without the sexy femaie characters, sexy looks always boost the sales.

I heard some scum dare to demonise guys who like the sexy protagonist (and the developers for making her look sexy) by saying something like "blah blah porn addiction", "blah blah objectifying women".
Know this:
1. "Porn addiction" basically means stop being happy and enjoying things, go work your ass off, gain status and bribe a woman into your life, be a woman's servant untill you die, or, should I say, until she "helps" you die sooner. Women, on the other hand, not only do they get away with any kinds of s*distic porn they watch/read, they're the biggest p*rverts, predators and PDFs - google the statistics - but, no one ever dares to blame them.
2. "Objectification of women" doesn't exist, neither does misoginy or patriarchy. Women objectify and are hostile to men, they see us as tools, resources and servants. Men love women and pander to them. That's why men live their lives on hardcore difficulty dying while doing dangerous jobs or at wars, or being abused by their wifes while women live their lives on easy difficulty geting all the priviliges in the world and leeching off of men and abusing them.

解谜确实够硬，少数的看攻略都很难坚持的游戏