Helicopter games released on Steam recently or at least within the last few months. Or even last year. :)

Upcoming and released sometric and top-down helicopter shooters inspired by Electronic Arts' classic 1990s Desert Strike / Jungle Strike / Urban Strike isometric helicopter shooter series.

These sims are usually from a first-person or "chase-view" perspective, and are more serious about controls and combat, although some - like the most recent Comanche games - are more sim-lite action.