You pretty much have to use UDP for packet transmission. You don't particularly want all the features of TCP, and so, according to the article below, some developers tend to use UDP and then cherry pick features of TCP to "reimplement".
Great article here, written by a developer at Respawn who worked on Titanfall. As a game developer myself, his articles are great starting points for thinking about networking in game development, which can be a completely different beast than web development:
http://gafferongames.com/networking-for-game-programmers/udp-vs-tcp/
EDIT: I refer to specifically the transmission of gameplay packets, the stuff that gets sent while actually playing. The other features of a game, like sending post game data to the central stats server, or logging into the game server, may or may not be implemented with TCP.