A fun idea with a really nice explorable table. I liked finding the credits in-game! Very clever.
Unfortunately there doesn't seem to be much in terms of difficulty progression (a symptom of the limited time, I assume), so after the first few minutes, there's not anything new happening, so it starts to get a tad stale. I also liked the idea of needing to stay in the boundaries of the dungeon map on the table to force you to get a bit more tactical, but you can just walk off to the side and find an open space and just mow the goblins down before they reach you (there's a reason the machine gun changed warfare).
I liked the d20 bomb mechanic; a nice use of the theme. Though because of the slowness of the dice falling, just shooting the goblins usually ended up being a lot more effective. So maybe an instant explosion at your mouse cursor that then spawns a d20 that rolls would be better? I did like the dice needing to stop before the goblins spawned though, since it created this natural wave-style entry of the enemies, and created the opportunity for the player to kick a die away to delay a spawn or reroll a number, which is a fun side-effect.
Overall, a nice idea that probably needed a bit more time in the oven. Nonetheless, good work!
(Oh, also, I didn't seem to be able to die no matter how many times the goblins hit me?)