I took another look at the charsets, and I agree - the regular version of Ή really does look too awkward. Also, since Greek uses several diacritic symbols (even if not all appear in your translation), it makes sense to switch to tall letters. I've made some code adjustments to address at least some of the potential issues with larger fonts, and tall letters are now used for Greek (web version already updated).
I also noticed that some lines don't seem to be translated, for example: "ON", "OFF", "GAMEPAD", "GAME OVER", "HIGH SCORES", "JETPACK", "TUNNEL", "TOUCH BUTTONS OFFSET", shopkeepers' names. Was that intentional, or did those strings get missed?
If you notice any other problems, please feel free to report them. And thank you again for your contribution!