There is checkpoints in the game. First mission will take you through the Sewers first, then Outside (first checkpoint), then the Mansion (second checkpoint). Restarting would mean you would restart all the way back to the Sewers. Masculine infected, Normal infected, Skinny infected offers different types of animations during sexttacks. You can easily figure each one out. Masculine infected are much bigger as where the Skinny infected are usually the one with a mask over their face (and the Normal infected are more lean). Each infected holds 3 animations of sexttacks except for the Dog and the Big guy with only 2. Getting grab from the front or back will initiate sexttacks. (Note that getting grab from the front or back would initiate different animations as well as getting grab with cloths on).
