You can make a F2P multiplayer shooter with unlockables that don't require money to unlock. However, you can typically pay to get these unlockables faster through XP boosts and what not. For gamers, the main benefit of F2P multiplayer games is that they can establish a decently-sized player base pretty quickly. Being F2P, there's no barrier to entry so pretty much anyone can try it out (and they do). The downside is that the business model relies on microtransactions, so you have to continually pump out new content and make it difficult to get unless you pay for it. Tribes: Ascend really doesn't need 50 different weapons but because they chose to go F2P, they don't really have any choice. If Epic makes a F2P UT game, I'd expect the same core set of weapons from the previous games, only with 10 different variants of each one. They may even go the T:A route and restrict weapons to specific classes, forcing players to unlock both the weapons and the classes that can actually use them, making XP boosters all the more enticing.