Knuckle Cracker

Sacrificing 5 or so PCs to buy time for a Sniper—and even then you need to have a spare PC or two because the sniper doesn't fire quite fast enough to kill every drone in time—it misses like every fourth one? Once you get a second Sniper up it gets much more straightforward...

1. Put CN at right/up place and firstly obtain energy pack.
2. Construct relay network so that you can reach up/left part of map also. And take into account the possible way of boy-runners from first left/up gate to CN.
3. On the way of relay construction obtain others energy packs, build several reactors and nullify 3 creeper emitters. Runner from first left/up gate not so dangerous and can't damage CN. Only be careful that on the way to CN runner can't damage relay.
4. Together with nullifying emitters build 2 snipers at the left and 2 pulse cannons and possibly one mortar.
5.  Then using PZ clear from creeper all upper part of the map so that no middle part runners can reach CN.
6. Then destroy gate with 1 runner, build Forge, reactors etc.  Start to attack middle part of the map by destroying gates and flip emitter. 

Good luck!  :)

I have started on the top right location too but didn't use snipers. Got the first energy with collector then went straight to the other 3 with relays. Put the relays that way so i also put 3 nullifiers too. Instead of snipers i have build 4 cannons and rotated them to intercept first drones - they are cheaper than 2 snipers, don't waste energy on that expensive sniper ammo and are build way faster. As soon as i nullified any emiter i did build another cannon close by and move it in the powerzone. I was able to clear all the creeper before if burrow to the lowest drones, then one more nullifier for the first drones. From that point it became easy :)