Happened to beat this game last night and thought I got lucky. Was able to beat it today. What finally helped me to progress is always upgrade the crossbow from each new level, then grind to upgrade the various gun towers (to at least lev 6-8) for my play style. The starting gun tower I maxed out and 2-3 of those really helps me out along with the barb wire things that I surround the tower to protect them. But I'm guessing highly leveled up items will help most people if they get stuck. For now, the game is still pretty fun so I'll probably grind for fun just to full level up all the items I want to try and the final set of gear to wear. Otherwise, decently fun game that didn't overstay its welcome for me. I just had to get used to grinding to level up the helper items.