Early Access launches Jan 20 - this will include a complete game experience, with a variety of content in multiple dimensions:
Single player or co-op with up to 4 players
10 stages of 4-7 minutes each, with a winning run taking about 80-100 minutes including intermissions and time paused
4 playable characters with unique traits
50+ spells each with differentiating mechanics and unique upgrades
30+ spell aspects that can fundamentally alter how a spell functions or grant access to build-enabling mechanics, and have their own special upgrades
20+ character talents and many more upgrades to tailor your build to your playstyle and invent new synergies
9 item categories, 30+ different equipment items and 30+ groups of equipment item affixes, not counting unique items
5 accessory item types with 70+ affixes
Interactions with various map features and objectives
6 different archtypes of enemies that can have various mutations on them and different wave patterns
9 unique bosses with multiple move sets
Interactive meta-progression that further allow customizing the difficulty and choices available in the game
Achievements for all unlocks + some more
Secrets, puzzles, events and more
The demo is freely available and will remain accessible indefinitely. It will be updated on EA launch, and continue to be updated as the main game is updated and will always fully represent the gameplay experience, with the only limitation being on how far one may progress through the stages. Any persistent progress will carry over from demo to the main game.
See the Roadmap for more details on things to come.