Grid Lock is not the usual zombies map meant for average players. No. It’s a one of a kind map which features something called Grids. You can lock and unlock grids. Locked(green) means that no zombies can spawn there, unlocked(red) means that you better find a green area. This map has a lot of custom features, like a puking zombie boss(just why?), sentry turret powerups, unique way to unlock perks, challenges, moving PaP, shootable easter eggs to unlock hidden rooms and many more.

Pros: Tug of war gameplay, just trying to hold and expand your areas in order to survive. The way you buy weapons is also very different, mainly that there are special “tiers” of weapons you can buy. How higher the tier, the better the weapon and the higher the cost. The Perks on this map have to be unlocked by shooting 1 of the 8 perk symbols. Every symbol needs to be activated by another weapon type( for example: A shotgun is needed for jug and a grenade for PHD). You can buy these perks near an upgrade station throughout the map, as well as raise your perk, wallet, break and grid limit. The best thing about the map are the hidden rooms, which you can unlock by finding and shooting small artillery pieces. You need to find as many as you can to survive and end the game.

Cons: This map is definitely not solo-friendly, with lots of runners and sprinters and an annoying boss. For co-op it is very reasonable. Some artillery pieces are very hard to find if you don’t have good eyes or a sniper. Most of the doors need an insane amount of points, it takes you about 20 rounds to reach Pack-a-Punch. The detail on this map could be a lot better, but the gameplay made up for it. Also the fact that you need to buy a certain weapon to unlock a perk can bother you, especially if you have 2 very good guns.
Bugs: Sometimes the player cannot place Bouncing Betties, they instantly vanish. You can jump on the ledge near the first PaP location and land on the steel beams, and zombies will almost never get you.

Final Verdict:
Level of detail: 5/10: Big layout of the map, but not much detail. Mostly always the same texture and other WaW textures.
Custom content: 8.5/10: A lot of custom content, but plain UGX-mod weapons, not even Black Ops guns.
Fun Factor: 8.5/10: This map is a lot of with friends, always preparing and capturing grids during the break, and trying to advance to the next floor and make it safe.
Replayability: 8/10: This map screams to be played even more, because you’ll never ever end the map in 3 tries or less. Every time you play you find new hidden areas and more secrets.
Overall score: 30/40
Link: http://ugx-mods.com/forum/index.php/topic,7622.0.html