Fuse is a character creation suite from Mixamo, which recently received a pretty huge new update allowing users to import assets they've created themselves.
The update, detailed on the app's Steam Community page, allows users to import clothing, body parts, texturing substances and more.
Why would you want to do this? Because Fuse can then export your custom character to various compatible Steam apps such as Garry's Mod and Source Filmmaker.
As a result of the official launch of version 1.0, many Steam reviewers have revised their opinions of the app. The $100 app is currently on sale at 50% off to celebrate its launch; grab it on Steam or just admire the video below.