It's like... you're a vampire... surviving...
I've never used pico-8 but it's always lovely too see game made for it. The game is well balanced enough, but I found some upgrades to be unnecessary and even detrimental. For example the one that increases wave duration i found to be really detrimental, since you basically end up increasing your blood consumption by a whole lot. The damage increase is also overshadowed by the weapon upgrade, i found the weapon upgrade to be a better increase in damage rather than... the damage upgrade. I did manage to reach wave 30 and completed the game, mostly with weapon upgrades and decrease blood consumption upgrade. I also thought the refill all blood was a little overpowered, but since it increases in costs over time I thought it was fair. In conclusion, it's a game with really nice visuals, and also mechanically has a pretty solid foundation.