Colors of Insanity is a lengthy Multiplayer compatible set of Escape Rooms. There are 10 rooms in total, each unique and more difficult than the last.
Optifine is recommended, but not required. Resource packs can be used as well if you're inclined to do so.
Colors of Insanity will test your Puzzle-solving, Parkour skills, and most of all, your Patience.
You can bring as many people as you can tolerate being cramped in a tiny room with, it shouldn't break anything. It's recommended that you make a backup or two though, just in case.
It was also made using as few command blocks as possible, with them only being used for gamemode switching, team assigning, and effect giving, everything else is completely redstone-based. Not because I can't do command blocks, but because I thought it'd be more fun to try and make stuff without them.
You start off in the first room, so don't wait for things to happen, just try your best to find your way out.
Good Luck!