Rush Rally has been written by a single person over the last 8 years, and does not use any 3rd party engine.
As I have been working on this solely on my own, the game itself has been written purely to see if a game on mobile can be driven programatically to reduce the dependency on art and audio. As a result, there are very few art/audio assets and all the tracks are 100% procedurally generated at runtime. This has meant that the install size comes in under 100MB for a game with 80 different tracks and lots of content, which on a mobile device is key. No one wants to install a game that is 3GB on their phone!
My aim was to cover every discipline of making a game, and to aim to make it as quickly and efficiently as possible. By every discipline I mean:
Every aspect of code (physics/animation/damage/audio/networking/rendering/etc etc),
Every aspect of art (I've modelled myself in the game as a spectator, all the models are simple and most are driven by simple textures and created procedurally, like the trees)
Every aspect of design (Rush Rally 3 has been much more or a challenge for this with a whole money and upgrade system!)
Every aspect of production (Bringing a game to market on my own)
I've spent nearly 20 years in the industry, and decided it was time to try everything!