Boosters are a common form of microtransaction across the videogame landscape. XP Boosters are easily the most common, but currency boosters and other forms progress speeders are out there as well. They're pretty insidious, as we can easily see with Resident Evil: Resistance, Call of Duty, and the hundreds of other games using them. Aside from the usual manipulation involved with microtransactions, boosters exert a level of control that keeps players hooked to a game so they can maximize their investments. And screw loot boxes being in a Resident Evil game, by the way.