If I insert a Special Unicode-Character (for Example , 267B, named "BLACK UNIVERSAL RECYCLING SYMBOL") into my Code and push it to GitHub, it will show as a set of random ASCII-Characters in the Screeps-Editor.

The GitHub-Page shows the correct Character (see https://github.com/LinuCC/screeps/blob/master/src/role/Zergling.js#L102 ), so the problem seems to lie between GitHub and the Screeps-server.

I am using screeps-grunt for now, which works great in that regard.