thank you ☺️
alas it took forever .. but depends on where you start counting 🤔
the game itself took 3 years - and it added many extras to the engine
but the engine itself was getting built on and off for 10-15+ years before that 🤔
it's hard to tell exactly when because it's a repurpose of my old flash engine ported to C/C++
e.g. in Zortch 2 I still use the multi grid approach for collisions that I made for my first flash game
with very few changes 🤔