Advancing Medium World Achievement
Advancing Medium World90
Complete ten different Classic Mode - Medium World level.On the main menu, choose ‘Classic Mode’ then select ‘Medium World’. On this difficulty, you are playing the Levels 16 through 25 of the game.
In these levels, you will encounter more enemies in each level, often around corners and in tight spaces, as well as more obstacles. Lasers are more frequent as well. You may start having some deaths in these levels but be persistent and you should have no issues completing each level in the time allotted.