"The first product was released in 1987. It was a 3D screensaver for DOS called Innermission. It was a 'TSR' which stood for 'Terminate and Stay Resident' program. If your computer was idle for a long time it would switch to CGA graphics mode and display a 3D field of stars moving towards you. Later versions added the ability to draw text messages with the stars that your viewpoint flew through. The last version we release in 1991 is still floating around the internet. It was shareware and cost $5.00."
--A History of Pie in the Sky Software's Products
InnerMission is a 3D terminate and stay resident (TSR) screen-saver for MS DOS released in 1987 as the first release of Pie in the Sky Software. The grounding in 3D provided by this was then leveraged in Corncob 3D and after that by the Power 3D engine. The final release of the screen-saver was released in 1991.