With the insane amount of skills that you can get as you level up your character, I'm sure there will be a good amount of ways you can be a successful sniper.
As to people jumping around all crazy all the time, it was the same way in UT. People jump, double jump, dodge all over the place all the time, but you can still get a hit off. mostly because the shock rifle hits instantly lol, but even if it wasn't, people tend to stop every now and then, even if it's for a second, thats enough time to get a shot off.
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