Screenshot of the title screen to Tentacularity
Guide the tentacles to the, ah, target areas...
Tentacularity is a tentacle sex puzzle game, for Windows, MacOS X, and Linux, starring a collection of our original characters, including Chelomnya and Michaela from Yuri no Yume, Oneko-chan from Catgirl Training, and two all-new characters. And a collection of tentacles.

The demo is a free download: Windows 98+, MacOS X 10.4+, x86 Linux; the full version is available from the HentaiSenshi Arcade. You can also buy Tentacularity from BMT Micro: Windows version, Mac version, Linux version.