There are two leaders on the sniping scene right now: Sift Heads and Tactical Assassin.
Sift Heads is the fun one, with more substance than Tactical Assassin. You have to get creative to solve the missions, you get money to buy weapons which actually affect gameplay(unlike Tactical Assassin 2, I might add) and Vinnie is a fun character. It's more complex and more like a real game you might find in an arcade or on a game shelf.
What Tactical Assassin lacks in substance, however, it more than makes up for in style. It's more realistic than Sift Heads, and you can't help but feel a sense of accomplishment when your target's head becomes a giant gaping hole and the mission accomplished screen comes up, like you actually just killed someone. Tactical Assassin is much more simple than Sift Heads, you just choose a scope, wait for the target, and blow his brains out.
This is deffently a hard one. Tactical Assassin was always my favorite and I played it every time I got on here. I played sift heads last night and was blown away. I would probably have to go with sift heads because of the graphics, mission selection style, gun options, and the story behind it.
I wasn't talking so much about the original Sift Heads and Tsctical Assassin then the series themselves. Go play Sift Heads 4 first then make your decision.