There's only the tutorial level, but you can play it as a sandbox after beating it. Try to get your writhing mass to 1000 or the 2000 max for that level. For more powerful machines run the Ultra Sandbox Edition build and start with ~3600 writhing mass to see what a real swarm feels like.
Update: now HTC Vive Wands are supported!
Here's the playthrough of the tutorial level: