Our approach at Linguicity and Linguicity World is for the reinforcement of language vocabularies through multi-language word games. Both are apps (two-player game and a solo word journey, respectively). The intent is to have players think in more than one language at a time. They really reinforce languages that one may already have some knowledge or interest in.
Image is an example of playing an Irish word for double points for being in the native language at that game level.