> Reaper is currently a de-facto standard for game audio design

Such a wide and strong claim, I'm not sure there is a single de-facto choice specifically for "game audio design", I've seen most major DAWs, including Reaper, to be used for game audio. If anything is close to a de-facto standard in video game audio, it'd be Wwise and/or FMOD as audio middlewares, then whatever the artists happen to be familiar with for the actual production.

Unless you're talking about some specific genre here, either music- or game-wise?