Frozen Synapse
The game mechanics are neat, and I am a fan of the presentation -- not just the cyber-blue aesthetics, but also (and especially) the excellent soundtrack. But I just don't care for the balance of it. I'm still super-early in the campaign, so I wouldn't exactly call it "hard," but it does require a level of attention and intricacy that I'm not really willing to spend on a video game (edit: yeah I guess that's not true).
While planning out a turn step-by-step is pretty fun, there are just so many variables in the execution - that is, potential, unknown enemy actions - that the pre-emptive simulations seem more misleading than unhelpful. Attempting to predict the AI is one thing, but I feel like there's too much guesswork in estimating weapon range and accuracy; the kinds of things that might be resolved using the simulations, but those results just aren't reliable. And even though the number of units you're given seems to generally be pretty low, some missions don't allow for cautious play.
Anyway, it seems pretty well put-together, but I don't think I have the patience for its learning curve or strategic nuances.
Progress: Gave Up -- Did some skirmish, finished the first couple campaign missions