Simmetri is described as 'creative toolbench and sandbox for building interactive 3D experiences for VR and screens'. There are eight alternatives to Simmetri for Windows, Mac and Linux. The best alternative is Adobe After Effects. It's not free, so if you're looking for a free alternative, you could try Hitfilm Express. Other great apps like Simmetri are NUKE (Paid), Isadora (Paid), Autodesk Smoke (Paid) and Notch (Paid).
Adobe After Effects is the premiere digital video effects software used industry wide for film making and TV production as well as creative work including high-end video intros and audio-reactive music visualizers.
NUKE is a powerful compositing application that delivers unparalleled speed, an efficient multi-channel scanline rendering engine, and a first-class feature set that is unrivalled in the desktop market.
Autodesk® Smoke® software is a leader in editorial finishing for high-quality commercial and broadcast projects. Smoke offers an end-to-end finishing toolset that combines intuitive timeline navigation with advanced 3D finishing tools.
Notch is the game-changing real-time visual creation engine that keeps up with your ideas. From motion graphics to interactive installations to VR experiences to the largest performances on earth, it helps creators rediscover the joy of creating.
Smode is a real-time 2D/3D creation, compositing and video-mapping engine developed by D/Labs. Everything with Smode is real-time: you can change any parameter at anytime without having to make expensive re-renderings.
Tooll is an open-source solution for creating interactive 3d content and animations. It combines the best aspects of animation, compositing, and coding into a lightweight and intuitive UI. Your designs can be shared as executable or rendered to movies.