Here are two screenshots:
First you need to create a world, for that you enter in new. You move with the arrows and jump with Shift. To put blocks you need to left click near to the character and to destroy them you right click them.
With the S key, you can save the game. In the menu on start of the game, you can enter the saved game.
The loading/saving time has been improved. Now it takes like 4 seconds only.
Go to the game
FIX:In the saved game, you cant put more blocks, but you can destroy them. This is because an error with the array.