Dungeon Defenders

In order for a level to be considered completed with 4 active players, 4 players must be present during initiation of the final wave, and stay in the game until the map is concluded. With a great tower setup, it's possible to do this by yourself as long as you have four controllers.

If you choose to solo this achievement, your towers will need to be well placed and they'll need to accommodate for the extra enemies that will be spawning. In the case of Glitterhelm, monk auras and huntress traps will need to be constantly repaired due to the high volume of enemies, so it's best to create a setup without them. On medium, a standard harpoon and bouncer blockade setup can take care of nearly everything on every map. I actually find that harpoons placed close enough together to not allow enemies past is more effective than using blockades for that purpose, except in areas where ogres spawn. The idea is that you want more than a durable setup: you want an impenetrable setup. The multiple placements should allow for enough trajectory possibilities to make up for the fact that harpoons cannot lead their targets.