The Grits project page says Grits was designed "using Google's technology stack". Unfortunately, they mean it literally because Grits dies with JS errors in any browser that is not Chrome and the latest version of Safari. Grits requires Google's Web Audio API, which is currently only a working draft spec.

  Web Audio API is not supported in this browser
  TypeError: this._context is null
  https://gritsgame.appspot.com/scripts/core/soundManager.js