how did you do that?
I got all the upgrades and after the first half of the time, it jsut becomes a boucne aprty with level 30 cells and you are lucky if you can damage a clsoe cell below level 30 and snatch it befoe any of the dozen level 30 cels around you eats it...
only always get up to 70 or 80% of the overeat bar filled at best :-/
I had a consistent strategy:
firstly I think it is a great statistical anomaly if you can finish the game before having all upgrades, but that's also why I had all of them when completing it.
secondly: when starting try to just eat whatever, (like i also kinda forgot the early game as it is something you just do well automatically). but from the moment the level 30's spawn in, begin going close to them, and use the damage upgrade (you have a clear visual representation of it going off) and try to be as close as possible to them. the easiest way to eat them, is when they are coming to you, chasing (as you probably have realised) isn't that efficient, but when you time it correctly, and they are coming to you, (or bouncing against a wall) they are free food. just do this for the time.
reminder: you kinda needs nearly every single upgrade bought, (there are like 2 or so that you can skip, like the more damage ones)