Operation Flashpoint: Dragon Rising. I wanted so much to like this game, but the developers spent way too much time focusing on minute details for "authenticity" (like setting speakers up next to tanks to get the exact sound) and not enough time on basic mechanics.
The biggest problem I had was the squad. To have a good squad based game you need one of two things: Good AI or Good Commands. Dragon Rising had neither.
Firstly, the command radial (why do they have a command radial on the PC version??) was horrible. If it doesn't pause the action at least give us a way to go back if we make a mistake. It was way too easy to select the wrong sub-menu in the thick of battle, and if you did the only way to go back was to close the menu and reopen it. That's just poor design.
Also, I liked being able to order a flank, or ROE, but I couldn't order them to go to a specific spot. Sure I could order them to a general area, but they'd always move.
I have two examples. In the first one, my squad was protecting a town from an enemy assault. Thinking tactically, I figured it would be better if my squad took cover inside the buildings. They refused. Every time I gave them an order to move inside the house, they'd make a perimeter instead.
In the second example, I ordered them behind a wall to my left, only to look a couple seconds later to see that they had taken cover on my right instead.
On the wrong side of the wall.
It seems like the devs were counting on the AI making up for poor commands, but the AI is so terrible that it reaches comic levels. What finally turned me off the game and made me sell my copy was the fact that the AI wouldn't register if you were in front of them. I was blown up four times in a single weekend. Three were when the AI shot a rocket at a tank with me standing in the way, and one time they bounced a frag grenade off my head and landed it at my feet.
It's a shame too, because the game had enormous potential. It just couldn't live up to it, and the fault is entirely with the developers.