I haven't played the game, but here are a few things I suggest to add/redo. As the sidescroller games are quickly losing user interest, you could add new concepts or completely alter the old ones. Inventory system eg. Red spot, STW, Ultra power, Fire fight and a few other games have had the inventory system. Personally speaking, these fancy schmancy cool things able to carry a tun load of stuff is getting boring to me. Player could put an entire mountain within them without breaking out a few sweats. Cart wheels, barrows, stationary depots, military backpacks limited to hold a few items are new concepts. While moving around a barrow or cart wheel sounds weird, I only named them to cross the idea. You could add other new features too. New smart MPCS eg that could be hired and deployed in watch towers, infirmaries to heal the player, infantries to keep the front line busy, vehicles to move units, choppers to cut down any air resistance, etc. If this game is not going to be a RPG/RTS, then again things could be twisted a little. Different types of bombs, bombs with the ability to change terrains (Blowing pits/ setting huge fires), chemical weapons to poison, blind, torture, mutate, infect, or kill players. Tech labs that could be built over time and make remote weapons to control other players, make them to do something, weapons to disarm, disembowel, disfigure, disable, disjoint, guns that kill with a single shot, devices to make players invisible, reincarnate, capture other players and more. Heck, you could even turn this into a magic game with players able to brew potions and cast spells haha.
I hope my ideas were interesting to take a look at, if not, sorry to bother.
I'm the Empty Bound. Set me on fire, for I don't care a hoot.