That title is broken bro, but it depends on what you're looking for. Here's a few: Anti-squad: It's decent, there's a bit of a story involving a Mexican drug cartel, but mostly it gives you a lame excuse to shoot stuff. I didn't really enjoy it, mostly because of the IAP and the fact you can't reverse moves when you make a mistake. Rad Soldiers: Amazing, it's f2p, and has a small learning curve. There's no story, but the missions get challenging and reward you pretty well. The real meat of this game is the online, it just needs some level restrictions, because you can get matched with higher levels easily. Call of Cthulu: It's got a great story, and some nice set pieces. The learning curve is kinda high, but I liked it. Shadowrun Returns: Never played it, but I've heard it was fun from reviews. This is iPad only though. Xcom: bought this a while ago, but never got to play it because my phone sucks. I've played it on ps3 though and it is amazing. Requires a lot of planning and strategy and has no IAP, but it's $20 and $10 when on sale. Wizard ops: It's online only, which sucks, because the tactical gameplay is very deep. There's no story and the IAP isn't extreme, if you can handle only online battles you'll enjoy this.
Alien Versus Human also; good caliber traditional X-com clone. Breach & Clear is a tactical squad based close combat game. Arma Tactics might fit the bill but I haven't played it yet. Frontline Tactics is a free to play successor to Tactical Soldier. LostStar Tactics has more of a science fiction spin. Uniwar War of Eustrath