You are a snake. Not a normal one, though. Unlike the others, you were born with two heads.

Alone in an unknown underground place, you must find your way to the surface. For that, you have to learn how to use your unique movements, as you control both of your heads at the same time. Climb walls, open doors, push blocks, manipulate gravity and even find the mysterious magical food, as you challenge your wits and reflexes.

It's been free for a while but it's recently gone offline only:

Over the years, our server has been racking up costs, and the now-unsupported software it was running on finally gave out.

All online services have now been migrated into permanent offline features. We made sure nothing was lost.

• The Level Editor now saves levels directly to your disk […]
• All community-created levels […]
• All-time high scores have been immortalized […]
• New high scores are saved locally […]

https://store.steampowered.com/news/app/752600/view/512967793587520222