[88stacks]

I think building a custom physics engine might not be the best way to go. Its a lot of work and super complicated to get right. I'd be worried that focusing on the physics will send them down the wrong path. That given I really do want to see an open source and widely adopted physics engine. I too have used bullet quiet a bit and it worked for my smallish experiments.

[capableweb]

Seems like they accommodate using custom/third party physics engines as well, according to the post. The built in one is probably just gonna end up "easy to use, get started and just works", but if you need something better, integrate PhysX yourself.