2. Keep cleaning this room. (but it doesn't mean the same as #1).
3. Keep tidy this room.
Sentence 1 is of course grammatical and what about 2 and 3 ?
Are 2 and 3 grammatical?
As you can see from the icons above, #3 is not grammatical. #2 is possible but it means "You have started to clean this room and I want you to continue cleaning it" or it means "You have cleaned this room more than once in the past and I wish to you clean it again in the future, more than once".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.