Defense Grid: The Awakening is a typical tower defense game by Hidden Path Entertainment. There are plenty of tower defense games on the Internet, which are majorly free-to-play; therefore paying for it would be overkill. Surprisingly, tower defense games are still very popular, if they are made properly, they can be very addictive. Time flowing by as you make a defense system that can withstand anything (and everything) which the computer throws at it.
The plot of the game is set in distant future, where you must protect the last of mankind from alien invaders. To make the long story short, you have to just prevent the aliens from taking power cores. On each stage, aliens enter the map and travel the shortest distance to the power cores, and make their way to exit. If they make out with a core, the core is lost; if they make out with all the cores, you will lose and you must try again. To prevent this, you must build defense towers in order to stop the aliens; there are different varieties of towers: gun, lasers, cannon towers, concussion towers, meteor towers, missile towers and inferno towers (which are basically flamethrowers) etc. However, the more powerful towers cost more resources, and the only way to earn resources is by eliminating the aliens. Hence, on each level, one must design an optimum defense grid.
To make the game more challenging and difficult, aliens come in a different varieties. There are juggernauts (shielded, non-shielded); they are huge monsters, who are extremely difficult to kill; there are decoys, which can absorb a great amount of damage, so that aliens coming behind them remain unharmed; there are speedy aliens that can quickly race through your defense grid, making it difficult for you to damage them (this is where the temporal towers play a significant role; they emit an electronic wave they temporarily slows down all the enemies, including decoys). There are flying aliens that can go past your defense grid. There are alien boss that shields any other alien that makes contact with it, etc.
Defense Grid has 20 levels, that will increase in difficulty as you proceed with the game. At first, the aliens will travel a long, linear path that is easier to defend, with only one exit. As you proceed, the levels become more difficult as there are more than one entrances to worry about. The number of waves increase; at first, you will only get around three to five waves per level, however, as the difficulty increases, game can throw waves anywhere between three to twenty waves. The most difficult levels are the open ones; there is no fixed track on which the aliens will travel, but an open ground, which you have to mold by placing towers, and creating a maze. The game is really well balanced! Sometimes, it's very difficult to stop some advanced waves without losing some cores; thankfully, there's a very useful checkpoint system.
The open levels provide a very good replayability as there are unlimited number of modifications you can do. To further increase the replayability, there are leaderboards to compare scores with other players. There is also a challenge mode, which increases the difficulty, and decreases the number of modifications and towers.
The 3D graphics engine isn't new, however, it is better than other tower defense games as most of them are flash-based. The sound effects are one step ahead from most of the genre; there's a guide which provides you commentatory and guides you what to do. However, he does repeat a line over, over and over again.
Defense Grid has a very addictive gameplay for a budget game; you can easily lost the track of time while playing it. At times, I didn't even realize that I'd made it through the complete level and wanted to have more, which is a good sign.