Start up the game Vectorman
(First not the second) you can change the difficulty in the options but its not necessary.
It is possible to farm Photons from the pink flying enemies, a short way into the first
level after fighting the 2 rock enemies you will drop down to a new area, to the right of where you drop down there is a location between 2 pillars where there will be 4 pink flying enemies flying around, you can kill this (
to shoot) and walk away from the area and come back for the to respawn.Note the enemies do not always drop Photons when you kill them but when they do they drop 6 Photons at a time, be quick to pick them up as they fall to through the ground if you dont pick them up fast enough.Do not worry about the time limit as you will have plenty of lives and using the farming method you wont be in short supply of lives.
Using this method it took me around 15minutes to get the achievement.
Here's a shortened