If you're following the road map then this should be the last playthrough. Select play game then scroll down to time attack. The goal here is to select an area then select the level from 1-5. After the level begins you need to finish that level in the time given. The times vary. Use the few tips about hitting the bombs near bigger enemies to clear the waves fast. Once you get the hang of this and see how it works you should have little trouble clearing each time attack. I will tell you this. If you do fail and the time runs out it gives you the option to continue or quit. If you do continue the time will not count and you wont get credit for beating it. After you beat each time attack within the time given it will put a line through the box showing its complete. I started on level 5 of each area to get the hardest ones done first. Overall they're all pretty easy though.