Well, I'm working on a web-based real-time multi-player game, and I'd say that UDP would be very welcome by me. When I'm on a good connection, TCP is fine and things work perfectly. But as soon as my connection becomes just a tiny bit unreliable and packets start dropping, it becomes completely unplayable, as TCP has to retransmit those dropped packets before any new packets are processed.
Since all we get is TCP right now though, you can take advantage of that at least and easily do things like send deltas instead of absolute positions, and even things that depend on reliable order of transmission (which you can't rely on if it were UDP), in order to reduce bandwidth use.
Since all we get is TCP right now though, you can take advantage of that at least and easily do things like send deltas instead of absolute positions, and even things that depend on reliable order of transmission (which you can't rely on if it were UDP), in order to reduce bandwidth use.