This was a game I worked on the side during my first years of college. This is an online multiplayer FPS for around 20 players. I just followed my ideas and added whatever I wanted for fun.
The idea was to make a futuristic FPS that would focus on information flow and more esoteric strategies. I wanted to make the player feel he was in an advanced suit of armor, and so I added complex functionalities.
The primary weapon was customizable in depth, and the secondary weapons never dealt damage directly, and could be detrimental to your team if misused. Each one had 3 modes, and an additional special on a cooldown.
In the end, the game needed balancing to be more fun. The energy economy was too slow, and the time to kill maybe too high. If I were to remake the game nowadays, I probably wouldn't make it an FPS because it makes it a lot harder for players to focus on the more interesting aspects.
The game itself used Photon for its networking, because Unity's default solution was really unwieldy. I chose a mostly client-validated approach, because it was simpler to write and nobody was going to hack the game.
Some weapons were a challenge to code considering the online limitation, especially the Magnet, which I had to make a lag resistant algorithm that would still need you to be accurate with it.
The online component made it harder to code and test, but allowed for some cool LAN parties, and I had a lot of fun organizing my code for maximum clarity and flexibility.