alright now that as of 4/14/2018 2:28 pm my scoreboard says I've survived the longest, i think i can safely say the game is fun, walls cost to much and explosion enemies deal to much damage to fully upgrade walls. i think the limit for survival is probably around 140 at minute.
the muramasa artifact has a bug, it does what the tool-tip says but it also quarters your damage, so right now all it really does is give you times four reward