Gameplay only exists in endless mode as far as I've played, as there is still no proper 'mode' select and the stage immediately begins as you enter the game.
The controls are a bit difficult for those inexperienced with bullet hells, but can be mostly adjusted to your liking.
The lack of permanent progression also makes the stage extremely difficult as time goes on.
No live multiplayer service exists, which is unsurprising for this genre of games.