Really amazing game! By far my favorite submission I've played yet! I like the way the difficulty changes between rooms, and the way the enemies are balanced with speed and health. The checkpoint is a nice feature to have. The whole dungeon was really well-designed. The big spiders at room 8 gave me a hard time for a bit, but now room 9 is my struggle. Haven't been past room 10 with the 4 shooters in the courtyard. I'll definitely be back to make more progress though!
Also, the scaling thing was an issue we had to figure out with our project as well - it depends on the browser's zoom level. We found we had to go into Project > Project Settings... > General > Display > Window, and under Stretch, changed Mode to viewport. We also changed Aspect to keep. If I remember right, that's all we had to do to fix it.