Games were cross-assembled on a VAX (using a modified version of the DEC macro assembler). I never saw the "blue FORTH box" but it was probably a ROM emulator

Games were cross-assembled on a VAX (using a modified version of the DEC macro assembler). I never saw the "blue FORTH box" but it was probably a ROM emulator of some kind that you downloaded code to, with some FORTH words for doing low-level stuff like debugging, resetting the target and diagnostics. The game itself was not written in FORTH. I'd forgotten that some programmers depended on other people keyboarding their source code. I think this was largely a coin-op thing; the other engineering departments never practiced that.