The phrase "additional loot" means extra or bonus things that are gained, usually in the context of getting more rewards or valuables.
Sentences with «additional loot»
Once the main missions are tackled, players are free to explore the city, and take on the side missions to gain additional loot and experience. (glitchcat.com)
There is even a daily challenge system that rewards players with additional loot and experience for character builds. (igcritic.com)
Rather than paying for the specific skins you want, you need to pay for additional loot boxes to open. (pcmag.com)