Yes, you can.
Viewing post in can i use premade games
Just to be sure, is it okay to submit a game that was already completed before this jam, or do you expect at least some of the work to have been done during the jam period? I have a text-only game that I'd like to submit, but it's much older than this jam, so I wasn't sure if that was okay! (I was hoping to do an update to the game at least, but real life got in the way unfortunately...)