Stunt Rally is a sandbox racing game with a huge number of tracks (172 in 2.6) and lots of cars. It was originally forked from VDrift and features Ogre3D as a graphics engine instead of the custom (and less sophisticated) graphics engine in VDrift.
A video is worth a thousand pictures and a picture a thousand words so, instead of me writing a million of those, I invite you to check out the gameplay in the video that accompanied the release:
Also recently updated is Irrlamb. Those with incredibly good memories will recall this physics-based game originally appearing many years ago. I originally wrote about Irrlamb over 8 years ago on Free Gamer, and the previous release (0.1.1) is over 5 years old if I'm not mistaken (it is hard to check since things have moved on since then i.e. Google Code where its development was originally hosted).
This release adds new graphical capabilities, new levels, gamepad support and various fixes - see the announcement for more details.
I'll also write a really lengthy... wait a minute! Let's link a video instead. ;)