I finished the game in coop with my sis. Fun game really! However balancing is a bit off, some levels are very hard vs others, some gadgets/characters definitely better than others, and blaster/sniper towers are definitely the most useful towers. Get the 100% completion on the game is tedious though: some level challenge like "do not be touch by X" is super hard versus another like "use only X towers" are super easy. Not super fun to try hard those challenges then, but fun to just finish the game in coop because the game is quite generous (took 11h for us to finish).