Hi,
just a small guide for those that aren't opposed to a little save game tinkering.

- Save your game in a new slot. You should always do this to make sure you don't crash your main savegame
- remember the spot you saved (counting from top, where the autosave is save0)
- go to C:\Users\YOURNAME\AppData\LocalLow\DreamWay Games\Espresso Tycoon\GameState\YOUR SAVE SPOT
- open save_X (x is your save spot)
- search for "availableChallengesStates"
- delete everything after that except the block containing "challengeID": "62b7b694-2ca7-4271-8508-dc6edae13d4b",

should look like this after deleting:

"availableChallengesStates": [
{
"challengeID": "62b7b694-2ca7-4271-8508-dc6edae13d4b",
"offeredCount": 224
}
]
},
"missionState": {

offeredCount measures just how often this challenge had been offered in your current savefile. tinkering with it won't boost your progress ;-) So the number doesn't matter. on a fresh save it's always 0.

After that you can get back ingame and you will only get challenges regarding selling snacks. since those are only to beeing accepted and will finish themself while just playing you can either accept them always when you do something ingame or even can start an autoclicker that pushes the accept and finish buttons when they appear. after that just keep it running fast forward, since you need to get those 1k days too ;-)

Some obvious additional tipps:
- you will need to offer snacks
- you will need to get to three(?) golden beans to get any challenges
- run a campain lvl. doesn't work in sandbox.

Hope this helps a little to reduce these ridiculous grind achievs^^

Start a sandbox game with
- enough cash
- disabled events (these will pause the game)
- gold beans at lvl5

After Loading:
- enable all researchs and max the budget
- employ a barista with the least hours possible (i think 4h)
- give the barista working hours
- now fast forward and whenever no barista is in your cafe just press the button at the buttom to skip time

This way you can cut down the 1000 days achievement to a ~166d grind