This is my take on the SE2 rifle, redesigned to better expand the game and overall vision. I have modified the weapon slightly to turn it into an energy pulse rifle.
Why? The reason is two-fold.
1. An NPC weapon is needed.
In any game with shooting mechanics, I believe players must be able to dodge incoming fire. A regular ballistic rifle simply would not do in this case, so I was inspired by Halo's approach. In that series, the most common projectile coming towards the player is the plasma bolt - a lower velocity projectile that is fired at the player in bursts.
By reimagining the rifle as a Plasmatic Pulse Rifle, this weapon may grow to become an iconic part of the identity of SE2. It stays within the grounded universe of SE by being tied to real science applications: the superheating of gas into a plasma.
"Plasma weapons convert liquefied carrier gas into plasma via an electrical arc, which is then encased in a magnetic capsule to prevent immediate dissipation." - description from Halo lore
2. Weapon diversity and lore.
The second main reason is I believe that SE2 desperately needs weapon diversity to compete in today's gaming market. A diverse collection of weapons are needed in any game featuring combat. Legitimizing the FP experience is essential for the SE game series to become a larger success. This is my reasoning to opening the door to energy / plasma weapons. Luckily, SE2 already has a lore reason for this advanced tech: S.P.E.R.A.
I envision the Pulse Rifle being the primary weapon of the hostile NPCs. The enemy will fire at you in bursts so players may dodge - leading to a similar fun feeling that comes from the classic Halo games. When this weapon is picked up and used by the player, they can fire at a higher rate that the NPC - leading to a nearly Auto fire mode. There would be downsides to this of course - most notably the accuracy suffers greatly with rapid firing and potentially a faster heat buildup that would result in a "Plasma Pistol" overcharge effect. The NPC would not be able to use this mechanic of rapid fire. Instead, they would have other weapons of with lower damage that are fully automatic.
Furthermore, this inclusion will result in greater creative freedom for the team - ship based energy weapons and shields are an easy sell once you explain the lore and back it up with a cool looking main weapon!