Wet Prope is a military project to create artificially-enhanced super-soldiers, capable of piloting large, powerful mechs known as Skelters. The project has seen both success and failure -- early attempts to create male soldiers failed, while later attempts to create female subjects showed far more promise -- but in recent years, almost half a dozen successful subjects have been produced. In the year 2030, 15 years after the project was initiated, it has become time to prove its worth; hostile squid-like alien creatures have begun appearing, and there's nobody else capable of fighting them.
Tenkū Danzai Skelter+Heaven is a sci-fi visual novel with very light rhythm game elements. The player takes the role of Otsuya, part of the Wet Prope project and the direct commander of the pilots. The game mostly proceeds as semi-voiced text and graphics, with occasional dialogue choices influencing the story and Otsuya's relationship with the pilots. Battle scenes play out from a first-person view from the cockpit; targets approach the center of the screen from different directions, and the player must press the correct buttons at the right time to "assist" the pilot. Performance in these sections also affects the outcome of the story.