Can EstyJS run in monochrome (640 x 400) mode? There were some great games in b&w, like Bolo and Oxyd [0] by Meinolf Amekudzi.
I remember studying the 'Hitchhikers Guide to the BIOS' [1], which was the only piece of documentation I initially had for the ST when it had just come out. If I'm not mistaken, it did ship with a C compiler and assembler.
[0] https://www.atariuptodate.de/en/authors/meinolf-amekudzi-104...
[1] https://archive.org/details/rearc_atari-st-e-tt-toolkit-b1-3...
Back in school in 1994 I was into DOS. But my friend insisted the ST was superior in every way. We wrote assembly games to impress eachother.
One day he told me he was working for a company making games.
I didn't really believe him back then.
Turns out the company in question was UDS (Unique Development Systems) and he was in fact making games for the ST.
We were 14 years old.
Must... resist... temptation... to write my own