Recently I found out on /r/lua about a Lua game engine called Amulet. It's open source (MIT license) and has nearly complete documentation (only thing I noticed lacking is some advanced sound stuff).
It runs on Linux, Mac, Windows, iOS and HTML5 (emscripten, fully working). There are plans on porting it to Android, too. There is an online editor with a lot of examples. The engine supports 2D and 3D. There is support for things like shaders, matrices etc. It's pretty fast from what I saw, too. There is a kaleidoscope shader 3D example in the online editor and it runs fast in a web browser.
The code is pretty simple and there's a bunch of cool stuff you can do, like SFXR (sound effects generated through a single seed integer), sprites from ASCII (of course you can use files too), etc. The style of actually running code is very similiar to Love2D too - you have a main.lua file, you run Amulet in its directory. The file name can be changed too, but then you have to provide it as an argument to Amulet.
I played around the engine a little bit (edited the Beach Ball demo to be like an actual game, with increasing gravity and points) and it's been cool so far. It's a very different approach compared to what I have tried so far, but it's intriguing. I'd recommend giving it a chance, but of course you don't have to leave Love2D
Just in case, I'm not the developer of it and I'm posting it purely to ask what you think about it.