Sentinel 3 Homeworld is a scifi themed tower defense game with simple game mechanics that is a lot of fun to play. While it does not do anything particularly new or different, what it does do is well done and enjoyable.
The game has a campaign mode consisting of 20 battles. Some of the game maps are used more than once, so there are less than 20 maps. As the campaign progresses, you will unlock new ground weapons, ship based attacks and boosts, and abilities for your commander.
The commander gets experience and money for each battle. Every 5 levels up to a maximum of level 20 the commander can purchase a new ability. These range from powerful meelee attacks, to passive helper abilities. The commander also has health, strength, shot damage and morale stats that can be upgraded when he levels.
Ground weapons range from basic lasers, mortars and air to air missiles, to more powerful lasers and the high damage sniper unit. There is a nice variety of weapons letting you be creative with your defenses later in the game.
Enemies come in two basic flavors, ground and air. Some weapons only affect one type or the other. There are several variants in each, ground enemies consist of slower tougher mutants, and faster moving insects. Higher level versions of the enemies can take more damage. There are also air and ground boss units, as well as the queen boss units that spawn a group of insects when they are killed.
The maps all use the same graphic tiles, with some variance in colors. The main differences are the route(s) the enemies take and how many barriers there are to defend. In some maps you'll defend a single path against larger waves of monsters, while in others multiple paths may converge at one choke point or you may have to defend several paths at once.
The 20 campaign levels generally take from 20-40 minutes each to play. The final level is longer, taking 1-1.5 hours. All in all the campaign is 8-10 hours long if you don't replay any levels, which you likely will do to get extra money for weapon slots and experience to upgrade your commander.
There is also a Classic mode where you can play selected maps with specific weapon load-outs. These are meant to be skill challenges, and you do not earn money or experience from them.
In addition there is an Endless mode where you defend a map as long as you can last against waves that slowly get stronger and faster. Endless games can go for hours, depending on the map and difficulty level selected. Endless maps are unlocked by playing the campaign, and you do earn money and experience when playing them.
And as for difficulty level, there are four for each map. These range from Easy to Psycho, with the enemies getting stronger in the higher levels.
All in all the game is well worth the $8 price tag, and even better if it's on sale. This is a fun game, that would also be good for someone who doesn't have a lot of experience with the tower defense genre. The first two levels of the campaign teach the player the basic controls and it is very easy to pick up and play.