I actually enjoyed the 700 zombies fight (This wasn't in the tutorial, this was after a while of actual gaming), it was chaotic and fun. My problem was I didn't feel like there was enough opportunities to leave early to try and get some level of advantages. If this is the intent of the game then that's fine, I understand how boring a small group of zombies would be, though I think where it's at is a bit high. Perhaps zombie hordes of about 30-40 ramping up from there would be more manageable for those who want to take risks while also not seeming overbearing for those who want to take it slower.
I'll try giving another test when V2 is released and perhaps record it as well so it can be a fun silly experience for us all ((Yes I did wish I recorded my several hundred zombies encounters for ya to watch)). Best of luck and, to be honest, I kind of like BlockchainZ, the direction it looks like it's going is an arcade-y colourful zombies experience which takes itself just seriously enough to keep more experienced players involved while having just enough colourfulness and silliness that it's entertaining for those adhd gamers who want action on action.
I wish you the best of luck with the project :)