[+++] New gamemode inspired from bejeweled 3's diamond mine

[Fab052]

it's basically endless cheese but with some twists:

• a timer that starts off from 1 minute
• after 10 completed cheese lines you go deeper into the cave (thus, leveling up)
• when you level up your timer will increment by 30 seconds
• at the very beginning of the game the cheese you have to clear is pretty easy, but the further you get the cheese gets harder