Viability: I found the game to be playable from start to end, with mechanics that go well beyond what we covered in tutorials. I appreciate the subtleties of the character design, with divergent paths and clear rewards for exploration. All this needs is more: more levels, more tangible rewards for collecting enemies, more music and enemy variety, etc. But do not be discouraged: It is a good problem to have when your players want more of what’s there :)
Presentation: The art is charming and clear. The combination of large “pixels” and small ones is very interesting! It makes it look like the graphics are a combination of different retro eras. The one thing I would suggest is to create a visual feedback when the players gets hit (other than the UI), either by instantiating a particle effect or even bumping the player back a bit. the first solution can easily be done with a Condition area hit/Create object and adding a simple particle effect. The second requires a bit of programming, but is not very hard to do.
Theme: While the game is mostly a traditional action platformer, where a complex story is not expected, the themes of exploration and adventure come through. It is funny how the fire is the main character here, rather than the creatures running from it. In a further iteration it would be good to think about how role-playing a little fire could be explore mechanically: perhaps your character size grows the more you advance through the level, or you can leave little torches on from which respawn after losing. There lots of opportunities here!
Engagement: The difficulty was just right that I kept playing again and again until reaching the end. Moving with physics is hard but rewarding, and I am glad you fine-tuned jumping enough to make it fun to do. Overall, this is a fun one!