For me it was a mixture of the “Ole reliable” and something new. Sticked with the Engine I know (Unreal Engine) but as Solo Dev I didn’t want to spend to much time on Level Design, therefore I made a 2D Platformer. Also I used Reality Scan to get some models. Which was a complete new experience. And as a refresher I only had Contact with Enemy AI in a Gamedev.tv Tutorial and I rebuilt it and modified it (atleast I hope)
Viewing post in Are you trying anything new?
I'm also a solo developer, so if I do something new, it's normally building on what I've done before. One of the things I've been trying to do in the game jams I've done is to try to do a different style of game in each jam as I'm still learning and gives me a chance to try out different mechanics.
So far my exposure to enemy AI has been using states based on player detection, I would like to expand it into using algorithms to manage behavior, but it's a bit outside my skill set for now.