I'd be really interested to see where you take the game post-jam. Given that it was made without an engine, it's quite the achievement already. You really got a taste of what gamedev was back then, since I don't think there were any commercial engines around GB's time :D
You could go for a more puzzle-y route for combat - to defeat enemies with limited resources by exploiting their weaknesses and such. Something like Desktop Dungeons' puzzle levels if you know that game.
Good luck with your project! <3