but when i get lost, will often avoid saving and use them as a way to teleport back to where i was

The boy/Greak can double jump
The girl/Adara can swim underwater longer, also has a single jump glide well alone that lets her jump farther
Tall boy/Raydel can't swim, can double jump
when grouped together they can all double jump

This game does not have a map
New enemies spawning usually means you are going the right way

No fall damage in this game
Things can and will attack you while you are talking to other people/reading signs/pulling up the item bar to use something.
The other people can take damage well not being controlled, this can be turned off on the menu. it can be a real pain, cause one of them triggers a death for all. This doesn't turn off floor spike
damage, drowning damage, or crush damage

If a person picks up one of the items for a quest and the other picks up one. you can't turn them in. The pause menu will only show the number of items you have on the player you are controlling right now. You can pull out the item bar and drop them to let 1 person pick them all up
People will say different things to you when you are controlling different people

You can only open doors with keys if the player you are controlling is the one that picked them up
Some doors will stay open, if you see a door its best to open it

once you get to 3 rocks-small big small-that need all three people touching to open, you hit the point of NO RETURN!!! if you want to backtrack or go for achievements, now would be the time.