I, Zombie
12 Achievements
1,000
2-3h
Speedrunner
Beat all summer levels with total time lower than 15 minutes
100
13.54%
How to unlock the Speedrunner achievement in I, Zombie - Definitive Guide
The only real tip I can give you is that you don't need 3 stars for each of these levels. You can shave off time by sprinting past things, even if it gets a few zombies killed. As long as you pass the level, the time at the end will count.
Play through all the summer levels to begin with and try to do them as quickly as possible. When you complete all of the levels, there will be a total time posted at the bottom of the level select screen letting you know your overall time for that run. All you have to do now is go back and play through the missions again and try to get a faster time to bring down the total time to under 15 minutes.
Look for missions that you took more time than others as potential candidates to be done again with better time. Just keep practicing them until you get better. When redoing the missions, just focus on speed and not on saving zombies.
Once you shave off enough time to get your total under 15 minutes, the trophy will pop.
There are a total of 20 summer levels (the tutorial level doesn’t count). For this achievement you can just run through the levels as fast as possible without worrying about casualties. You don’t have to get three stars for the speed run.