Thanks! Really glad to hear you enjoy the game :). I had a lot of ideas for more maps with vastly different environments and experiences, but because I'm solo developing and currently enrolled in my co-op term, I only have a few hours per day to work on the game :(.
However, I am currently working on multiplayer that will have a lot more side objectives in a larger map and can be played by 2-16 players per room. You can choose to join random rooms or create password protected rooms if you'd like to try beat it with your buddies. It's hard to predict when it'll be done, but I've made a lot of progress on it and am trying to release it as soon as I can (before people lose interest lol).
Thanks a lot for the feedback too! I try to release updates while I work on multiplayer, so I'll at least have the soldiers balanced by the next update :).