Thanks for taking the time to read my post, I did put quite a bit of effort into. These types of upgrades are linear with a vertical tree. You can select which is best for the moment or area you are in. The module system i present would allow the user to upgrade into a defensive/offensive mods. However, Weapon module system could be a side upgrade to the original system i presented. Which means you can upgrade the system (How well it preforms tasks) or the chassis (How well it can defend itself) This system would act the same. The size of the weapons would impact its mobility. Slow heavier firepower, quicker lighter weapons. You could then upgrade your weapon systems to allow: Heavier Weapons. Max 2 slots with heavy weapons. or 1 slot with AOE weapon. (Cannon) More Weapons. Max 3 slots with light weapons Special: Replace weapon with more defensive item such as a shield, emp pulse or other special equipment that would prove more useful to one type of enemy than another. Heavy weapons could have longer fire times between shots, or a delay in switching between targets that would represent moving from one target to the next. While lighter weapons can rapidly switch between targets but does noticeably less damage. This is the import part: This system would allow creation of specialized items. Much like in firefall you would be able to create special items that you wouldn't have access to normally. THESE SHOULD BE BASED ON SKILL. NOT "DO x NPC MISSION" Achievements for skill should unlock higher tier items for the operator. You managed to fend off a huge special onslaught in XYZ district? Damn, that's impressive. You should have access to XYZ module. This would be more community drive. "Hey, can someone help me do XYZ achievement?" Increasing the interaction between players is always good. AS LONG AS these items are not Overpowered but still very useful. They shouldn't feel like a necessity to use. More like an extra player helping out.