Think you were too hard on yourself, I really enjoyed this! Found the enemies intensely stressful, if there was a little audio in there it would be genuinely scary. The animations were great too, you could definitely take that scribble animation idea and make it work in a full game, the damage scribbles were really effective (and a little horrifying). Building works well, thought I'd been super smart and surrounded myself with barricades only for them to smash through after a while.
Overall, great job!