i think the main problem porting open transport tycoon will be the graphix. it's even a bit messed on my pc too (in all resolutions). the original version was looking better i think. but this might be because of myself playing locomotion lately.
controls won't be problem i guess. you only use the keyboard for shortcuts or naming stuff. (vehicles, yourself, etc)
it will be nice to see a addictivlely playable game on gp32. plus the chris sawyer approach!