Collaborate!

"Have 4 Heroes on screen at once."

- BTD6 description

Collaborate! is a BTD6 Achievement that was introduced in Version 11.0[verify]. Collaborate! is achieved by having 4 heroes on screen at once in Co-op. Earning this achievement grants 50. The player must be Level 20+, since Co-op is required for this achievement.

Summary
Collaborate! is one of the easiest Co-op achievements to get and can be a quick 50 when earned. This achievement can be earned through regular play, however requiring the player to play 4-Player Co-op due to needing 4 Heroes on screen. It's not necessary to get if you just want the rewards but if the player is achievement hunting, it'll be easy for them to get.

Tips

 * Playing Quick Match can work, however sometimes players don't place their Hero which can make it tedious if trying to get Collaborate!.
 * Playing with friends works, as all 4 players can coordinate together to get their Heroes down as fast as possible for this achievement.