Games are more fun with friends.
Non-exhaustive list of adjustments and additions besides multiplayer:
Cap mobs at 175
Hasten tower spawn
Multiplayer leaderboards
Turret demolished on host may not be on client
Lasers fully synced
Add shop location to minimap
Prevent host from crashing at end
Rescale mobs for multiplayer
Elixirs maybe still not disappearing
Paralyze from paralyze turret not applying status
Boss HP bar not updated in multiplayer to reflect higher max hp
New character cards
Turret cloud not transparent on client
Add gears to end metrics
Some DPS (fire, poison) not applying to only the correct user
Mobs killed not unique
Allow reviving the fallen