Remember Terror From the Deep? The underwater X-COM seems like an obvious inspiration for Stirring Abyss, and there's a fair bit of the more recent and less damp Firaxis XCOM games in the mix as well. In Stirring Abyss, your squad of divers spend their action points crossing the ocean floor, firing spear guns at jellyfish creatures, and hoping the percent-to-hit plays out in their favor. It's also got an damaged submarine to repair and upgrade, pumping out the water to gain access to rooms with different functions like your Avenger in XCOM.
It's got another inspiration too. A short story by H. P. Lovecraft called The Temple, which is about strange things happening aboard a U-boat during World War I. Stirring Abyss moves its action ahead to 1958 and replaces the German U-boat with a US Navy submarine ominously called the USS Salem, but it's got some definite shades of the Cthulhuesque. Not just in its tentacled underwater threats, but the way you have to manage your divers' sanity as well as their oxygen.
Stirring Abyss is the work of indie studio Sleepy Sentry and is being published by Slitherine as part of their K-Project, where five percent of the profits from each game going into a fund for new independently produced strategy games.