Sentinel is an interactive audio tower defense game. It mixes strategic gameplay with a dynamic music system.
User reviews: Mixed (54 reviews) - 64% of the 54 user reviews for this game are positive.
Release Date: Apr 22, 2014

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Recommended By Curators

"Fantastic soundtrack wrapped in a visualizing and challenging tower defense coat that is incredibly challenging and more of a puzzle than usual TD fare."
Read the full review here.


“If you’re quite fond of the tower defense genre, then you’d certainly be wise to add Sentinel to your play list.”

About This Game

Sentinel is an interactive audio tower defense game. It mixes strategic game play with a dynamic music system.

The game takes place on a sequencer-like grid. As you add defenses, collect resources and destroy enemies, musical elements are triggered in time to the music.

Fight through 31 levels to clear the virus from the system.

System Requirements

Mac OS X
SteamOS + Linux
    • OS: Windows XP or later
    • Processor: 2.0Ghz+
    • Memory: 2 GB RAM
    • Graphics: Shader Model 2.0+
    • Storage: 750 MB available space
    • Additional Notes: Widescreen monitor required.
    • OS: OSX 10.5 or later
    • Processor: 2.0Ghz+
    • Memory: 2 GB RAM
    • Graphics: Shader Model 2.0+
    • Storage: 750 MB available space
    • Additional Notes: Widescreen monitor required.
    • OS: Ubuntu 10.04 or later
    • Processor: 2.0Ghz+
    • Memory: 2 GB RAM
    • Graphics: Shader Model 2.0+
    • Storage: 750 MB available space
    • Additional Notes: Widescreen monitor required.
Helpful customer reviews
8 of 13 people (62%) found this review helpful
0.2 hrs on record
Posted: June 23
This game SUUUUCCCKKKSSS. You play on a boring blue grid background where you place uninteresting little squares on a few different possible squares to kill squares and circles that come. No pathing for a TD game. There is very few things a TD game has to do right, and by having uninteresting enemies, bland similar towers, and a boring environment, there isn’t much to keep this interesting. The menu and UI are terrible and don’t seem to have a working or logical main menu. You can’t easily exit the game from the main screen, probably because too many people try to do it after playing this game. There is no story either. Then there is the terrible tacked on micromanagement aspect which takes away any possible enjoyment. Not only do you have to have to gather resources and use them to build towers, but even THEN they still won’t work. You have to spend each level turning power off certain towers that aren’t in use by clicking and mouse scrolling on them (not a very intuitive control scheme) and then click back on the tower you want to use and mouse wheel scroll up. This means you are constantly going between like 6-10 towers turning power on and off. When it happens they come from both sides, which is often, you then basically are screwed, as you can only have half effectiveness on each, then when they get through to the next towers you have to turn 2 different towers off, then turn the next two on, with the exact right amount of power, which you don’t know what that is and how effective it will be. See how that could be annoying to do continuously. There is no time to build and enjoy, you are just turning power on and off for basically 90% of the game. Management aspect doesn’t work in this TD, and just makes playing a chore. Add that terrible mechanic to the rest of the “meh” game, and you have a “stinker” as DP would say. 3.5/10.
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2 of 2 people (100%) found this review helpful
0.2 hrs on record
Posted: September 24
Sentinel is a tower defence game with a quite novel 'power distribution' mechanic, a nice visual aesthetic and some cool sounds/music

The problem is that it quickly becomes a memory test - you see what's coming but knowing what to build/how to spread the power often requires more advance knowledge - hence it's the sort of game you need to replay levels to complete them.

It then adds levels which require 'perfect' completion - which is just rubbing salt into that wound really??

It's just lacking some basic features which other TD games have - it has 2 speeds but no 'pause' that I can find for example - and no keyboard shortcuts for some things that I can find either.

There's no checkpointing/rewind system I've noticed which means if you make a mistake/want to try something else, it's the whole level to redo/retry

Oh and restarting the first level makes you sit through the unskippable intro each time - that's really, really annoying.

I still find myself playing it from time-to-time but it really did need a BIT more polish and a few more features
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28 of 31 people (90%) found this review helpful
1 person found this review funny
0.9 hrs on record
Posted: March 16
The emphasis on needing to get “perfect” levels killed the game when I reached the first gate. I cannot do it on any level. There is no “easy” mode or anything. You just have to get an absolutely perfect level to progress. Apparently this idea multiplies throughout the game for the rest of the checkpoints.

Mr. Brown, why not just have a simple progression system and just give an achievement for the perfectionists? The whole game is locked down basically :/

Like others have said, lots of mirco-managing, flashing colors, etc, but I didn’t mind any of it – pretty fun game for me and the micro-manage craziness actually had appeal… for the first 5 levels… till I got stuck… by needing at least one to be perfect. ^_^

Because of the craziness of switching your power back and forth from tower to tower, collecting money that’s falling, and using the manual tower, lots of things are happening very quickly – so to expect everybody who plays the game to be able to do that perfectly is a bit.. lame.

I never go for “100%s” or “max levels” or “all gold times” in games, I just like progressing casually. This is not possible in this game, you must be perfect... while you pay attention to 10 things at the same time.
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29 of 38 people (76%) found this review helpful
1.1 hrs on record
Posted: April 22, 2014
It's a simple, tower-defense game, nothing game-changing. But it's still fun, challenging, and forgiving at the same time.

Here's a quick look I did of the game. Feel free to skip around to get a general idea of the game and what you'll be getting into. Or you can simply read my summary below.

I'll start off by saying it's got a good atmosphere to go along with what it is. The basic premise is that you're an anti-virus program defending off viruses, and the visuals and music that accompany it fit their their roles well to put you into that world.

The basic gameplay is simple. You have lanes of creeps that mindlessly run into your core. The bare bones of all TD games. However, the game isn't as simple as plopping down a tower and forgetting about it. You have to allocate a limited pool of power to to each tower, and the more you give it, the stronger it is. So you're always frantically shifting your defenses around as the waves progress. That means you aren't staring at the screen and letting the game play itself, which is always a good thing. You also have to click little cubes and diamonds for ressources to upgrade and build your stuff, so you always have to be on the lookout for those. The game even grants you a free limited-time tower to help clean up some of the creeps that make it through, which is also nice. Nobody likes banging your head against the keyboard as the final creep runs into the core with only a sliver of health, ruining your perfect run.

The music is also good, if repetitive, but that's kind of what techno is all about. I also really enjoy the fact that the music changes as you add power to different towers, and that when the tower themselves fire, they also add to the beat. It's almost as if you're remixing the song yourself.

But now let's talk about some of the negatives. While the game does give you a good tutorial to get you started, it doesn't do a good job explaining the newer things you get later on down the line. It's all about trail and error. You also have no idea how much of a difference you're making when you upgrade a tower or give it power. You get a visual cue that the range has increased, but not about how much extra power you're giving it. A percentage or something would be nice to have. Also, the game kept on sending in new enemies at me that I had no idea how to deal with properly. The first being a big cube that only slows down when you constantly hit it with something. But the only thing that constantly fires is the free tower that's on a long cooldown. You also have to control it manually, so you can't allocate resources or build new things until you've finished dealing with the threat. Then the game snowballs into something you can't recover from, so you have to start over.

Then there's the problem of not knowing how effective a certain tower is against a certain enemy type. I got a tower that was supposed to be effective against shielded enemies, but when they came, even at full power it wasn't that great. And when you start throwing other normal minions into the mix, you're never sure what tower you should prioritze over another as they enemies bum-rush you from all directions. And not only that, it's extremely frustrating when the tower that's effective against certain types chooses to fire at another enemy, and the one it's supposed to kill struts by unscathed. There needs to be some sort of target priority.

But yeah, all of that is only a problem if you're OCD like me and want a perfect score. There's plenty of lives you can leak before you get a game over and have to retry.

So in summary, this is a solid TD game at $3. The game offers good content, a variety of enemy types, keeps you engaged constantly in what's going on, interesting setting and music (if you like techno), and is genreally just a good time waster. Get it now, or even wait for a sale when this game won't cost more than a dollar. You'll get some enjoyment out of it.
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10 of 10 people (100%) found this review helpful
2.7 hrs on record
Posted: November 11, 2014
I have mixed feelings about Sentinel...

As a TD game, you have to micromanage a lot of little things very quickly and keep checking the upcoming waves to know how to deal with each one properly, however, unlike most TD games, the strategy doesn't come from placement or upgrading, but rather energy. In Sentinel, you have a set amount of energy (and adding a tower to the field increases that amount by 1) which you can divide among your towers, to a max of 5 energy at any one tower. You can later reduce energy in one tower to give it to another, to focus your attack on a different lane. This is the main mechanic of the game and takes serious micromanagement skills. During each round, random extra money might fall from the top of the screen for you to collect, and dead enemies might drop special icons that allow you to upgrade or buy different towers, and while the game itself isn't terribly fast-paced, all of this happening at once makes for a real challenge keeping up with it all.

Outside of the TD, there's a stage-select map, which I actually quite like, apart from the gates you have to "hack". Every so often you'll come to a locked node that you can't get past without spending a certain number of "credits". Each stage gives you 1 credit for completion and 1 for getting through it perfectly (and bonus stages give just 1, since you have to do it perfectly or fail). As you get to the later gates, you realize very quickly that you'll have to go back to some levels and get a perfect on them if you want to continue. I find this a little frustrating, as in my (admittedly limited) experience with TD games, I've never had to do a round perfectly to move on to the next.

That's about all the bad I can think of for this game, though, and there's plenty of good to mention. First and foremost, it's just fun! The music suits the game very well, going from calm and relaxed to active and upbeat as you change stages, and it's always very unintrusive, letting you focus on the gameplay. Although it does take skill to use properly, I like the energy mechanic as an idea, being able to focus more on one part of the field at first, then spread out your power later, or turn off a useless tower that round to make a more needed tower a bit stronger.

The bonus stages really make you think about every little detail of the game, from which towers to place where, when to have them on or off, how much energy they need, when to sell them, when maxing out their strength isn't a good idea... the list goes on and on, and each one is very cleverly constructed to make you aware of some aspect you may not have known before, making it a very cool way to teach the player without sitting through a tutorial. One example that really jumps out at me is a bonus stage near the beginning, where you have to collect the early enemy drops to upgrade your towers, and then sell them because the upgraded ones are worth more, and that gives you the money to set enough mines to take out the remaining enemies which can't be destroyed by the towers. If you do it perfectly, you will end up with zero money, so there is no room for error, and you definitely have to know what you're doing to get the job done.

For me, $3 is absolutely a bargain. I'm getting a fresh twist on a cool genre, and I'm learning to think in terms of what makes the most effective strategy, not just which gun does the most damage. So far I've played a little less than 3 hours, and I'm maybe halfway through all of the levels, which means I can expect another 4-5 (after going back to do everything perfectly) for my money, which is considerably more fun per dollar than, say, going to see a two hour movie for $10.

It's not perfect, and it's really frustrating sometimes, but it's enjoyable unique, and that's what I look for in a game. For the price, I have to say yes, I do recommend this game.
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