So you take an open source game, and you modify it to add a language learning element.

For racing games I could imagine 2 side by side checkpoints and as you drive you need to drive through the checkpoint that is the correct translation, you could get a boost or whatever when you get the answer right.

THe difficult part of this is that you need a fun open source game to modify, you can create your own, but that can take alot of work... even more than the original task of learning the language.