Maps are locations that players can play gamemodes on. Players can access these in the lobby via the map queue areas. Maps can have obstructions that hinder your tower's line of sight, and these obstructions become more frequent the harder the difficulty of the map. Depending on the difficulty a map is rated as, players will either be rewarded more or less Gold and XP upon completing the mode. Completing a map on any core gamemode[1] for the first time will award you a medal.
Medals
Medals are a type of achievement that players can obtain by completing maps on either Easy Mode, Intermediate Mode, Elite Mode, or Expert Mode for the first time. Upon receiving a medal, players will gain 80% more gold as a bonus. This was added as a new way to grind for towers like Golden Ranger and Golden Juggernaut due to their costly prices. Other players can view your medal count when viewing your profile card.[2]
Carrier and Cow Annoyance are currently the only non-Event maps to ever be removed from the game.
The Simple map difficulty is currently the only difficulty to be added after the launch of the game.
It was created for the sole purpose of nerfing Ancient Sky Island due to the Barracks' Units being able to see about 95% of the whole map upon spawning, making it effective for grinding.
Cow Annoyance was temporarily removed and replaced with a different map in the 2023 Christmas event update which was due to the layout of the map being extremely good to grind Elite Mode when playing with Barracks.
During the 2023 XMAS Event, in Santa's Stronghold, cows could be seen trapped in cages, referring to the temporary removal of Cow Annoyance. (said cows are now no longer inside the cages)
The same reason can be used for Carrier, as it was removed due to being a fantastic Expert Mode grinding map.