Essentially it is a flash game, an enjoyable variant similar to the Candy Crush type game if you've ever played it, that will provide around 5-20 hours of fun. At its core its a puzzle game with strong elements of strategy.
The premise of the game is that you have to surround groups of zombies with the same type/coloured survivor to remove them from play. Survivors consist of the soldier, the policeman, the cheerleader and the thug, each providing a different voiceover when a group is cleared which is quite nicely done.
There is one 5 act/20 level campaign which should take you around 5 hours to complete. The learning curve is very well done which is good as there is only one difficulty setting.
A range of harder zombie types provide the bulk of the challenge is this game as you progress through the campaign. The simplistic gameplay is added to with environmental hazards that can kill off survivors or block more of them from coming through to reinforce the game board. Additionally you can have up to three power-ups to blast away groups of zombies when in a tight sequeeze. There are around 6/7 each individually adapted to provide a unique destructive effect when used.
There are three additional survival levels that you can play if you get hooked while the soundtrack is very basic.
If you are an achievement hunter it should take you between 14-20 hours in total to get the last one, as its a grinder!
Overall Id say the game does what it says in the store page. Its nothing special but it is enjoyable if you like this sort of game, as I have. If you are a hardcore game then this is probably not for you unless you like a dose of casual on the side!