The Sentinel series of tower-defense games has been well received since it began back in 2009. Now, Sentinel 4: Dark Star has descended onto the App Store, and i can't help but feel that everybody was hoping for something a little more from it.
More of the same
Sentinel 4: Dark Star is about as traditional as lane tower-defense gets. Enemies advance on you from a number of paths, and you must place your various gun turrets and other weaponry to take them out before they reach your HQ.
Advancing through the game provides you with different tower types to better defend yourself from the evolving enemy force. When used properly these work in concert. Slowing an enemy with one unit while they pass through corridor of machine-guns, for example, ensures that you get the biggest bang for your buck – and proves the only way to make it through the later stages.
Where the series does mix it up is with the titular Sentinel. This powerful unit is able to move between key points on the map with a tap of the screen, providing a vital last line of defense.
A refined system
A menu bar at the base of the screen provides an effective drag-and-drop interface to control Sentinel 4's strategic deployment. Playing through the game increasingly more units are added, but these touch controls ensure you are never overwhelmed.
Towers automatically upgrade as they defeat enemies. Keeping track of you more powerful units is vital because if they come under fire quick repairs are necessary. This is a simple process: a tap of the failing unit brings up a radial menu, with another tap on the repair icon returning the tower to full health. Upgrades and other options are handled with similar ease.
One of Sentinel 4's highlights comes from its structure and pacing. On the normal setting the game offers a good level of challenge, but it never becomes frustrating thanks to natural bottle necks and barriers in levels. It can be easy for a tower-defense game to swarm you but the pacing here is perfect, with greater challenges available if that is what you are after.
A coat of new paint
When the first episode of the Sentinel franchise dropped onto iOS, it looked impressive. Over the years the games have undergone a number of upgrades with graphical flourishes and new units being added to keep things fresh. Nonetheless, it has started to show its age.
That is not to say that it looks bad, but it no longer shines over the competition. Fortunately, the new lighting and explosion effects combine with the pulled out perspective to hide many of the larger is issues, while managing to not obscure the field.
The one big advantage of all this is that the game still works on the original iPad and iPhone 3GS, albeit with some of the visual effects turned off.
Still good, still the same
Sentinel 4: Dark Star does what it does perfectly, providing more of the franchises excellent gameplay and also adding a few of its own refinements. That, however, is all that it does. This makes it easy to recommend if you are after a traditional tower-defense experience, but there is little here for the more adventurous.