Thanks for checking out the game. I've uploaded the "TinyRL_post_compo.zip" file which contains an "TinyRL_2x.exe" which will upscale the game by 2. I hope this helps you out.
For drawing and user input I used SDL1.2 and wrote my own framework for all of the roguelike stuff on top of that.
The sourcecode is here if you want to have a look: https://github.com/bit-hack/7drl