This will no longer be the case, the game will have checkpoints.
The reason to add the checkpoints is that contrary to the coin-op arcade games, Shadow Gangs levels will be much more bigger and forcing the player to restart the level from the beginning is not compatible with game enjoyment.
Aside from checkpoints, there will be Ninja magic in the demo, you can thank Toni Galvez for it as I wasn't planning to add it for the demo and was leaving it instead for the whole game.
In the final game there will be different ninja magic types, but for the demo we will have one.