Goat Simulator started life as a joke created during an internal game jam at Coffee Stain Studios to "blow off steam" says CEO Anton Westbergh. However it was the response to a YouTube video that made it into a real product. "After about two weeks of jamming we had this goat roaming around a map and wrecking stuff, and we all thought it looked pretty hilarious so we uploaded a video to YouTube and it just caught fire," explains Anton.
From there it was fast-tracked into a real project and developed in an incredibly brief four weeks. Check out the interview for more interesting info on the game - like how the team made bugs 'a feature'. Then there's this gem on using the Unreal Engine:
"Unity is probably cool for a lot of games, but we're providing realistic goat simulation, and then there's little choice in what tech to use. Epic also loves goats, and that’s probably the most important for us."