The 3D GBA Rendering Engine was a project Jagex worked on for a while. It was mainly pointless but was put towards making a new model of RuneTek and experimentally used to see the capabilities their computers and technology was capable of. It was never released publicly (unless you count the fact that half of it was put into the program that supports RuneScape) but Andrew Gower often spoke about it to other players. Recently in a Q&A session with Andrew Gower, Andrew mentioned it. He said (in response to "Could you tell us more about the 3d gba rendering engine you worked on?") this about it: