So an idea for a possibly nifty system came to in. Basically in your R&D aspect of base management you'd have the option to create Prototypes or molds that could then be used for manufacturing equipment for your troops. 

Basically You'd:

1)Research the Concept: this would be your relative to researching new items in the old xcom. Though instead of being able to produce this gun, you'd get a free 'Prototype' which could be manufactured. This prototype would be a variant of the weapon, with it's own stats and traits (like the aliens)

If you choose to go to manufacturing this item, you can. Otherwise you go to 1b)

1b) Develop new prototype: You basically reroll the gun in hopes of getting a better version of the gun. 

2) Manufacture: Now that you have a prototype ready, you can set your weapons to mass produce. 

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Thought this would be a cool way to:

-add something simulationy to the game

-while keeping it streamlined

-adding more procedural generated content for the game,

Perhaps you could have little slots you can fill such as: enemy analysis, researched perks (things that you earned in the game and would be automatically applied to the gun) which could help with agency.