When you strip them down to their very cores, war games have a lot to do with numbers. You manage troop movements, pit the right force against the right enemy, and then wait to see who had the bigger numbers and whose force will be victorious. Exponential Invasion [$1.99] is, in a way, just that sort of war game, one that has stripped out every bit of visual fluff to lay bare the numbers game beneath.

Your numbers are white, and blue numbers make up the enemy's towers. You capture them by putting together a number that is higher than your foe's. The strategy lies in how you make that happen. Your force can absorb any smaller number, building itself up until its large enough to take out the enemy. But resources are scarce, and the battlefield is crowded. Doing so efficiently can be rough.

So you can tap any number onto an adjacent, smaller number, adding to your total if it's friendly or wiping it out if it's not. And you can take the blue tower with a larger number, but you'll quickly find that number must be larger by one, and no more. Otherwise you've likely done something wrong; your second force or third will find itself shorthanded. Then it's time for a quick restart and a new approach.

As you make your way through the game's 24 levels, you'll find yourself needing to be more and more strategic to proceed. You might be able to add up the perfect force to take down the tower before you, but a single digit may block your path. Figuring out how to move it to safety solves half that problem. Establishing how to do so without passing the move limit can be a bit harder.

Realistically, you're going to be able to complete every level with a bit of time and basic addition. There's no challenge in that. So Exponential Invasion is best played for a three-star score. When you complete a level, you're told how many moves you overshot—the most fun to be had is in going back to do better.

The only serious problem with Exponential Invasion is that it ends just as it starts to get good. The later levels are claustrophobic in the very best way, and they begin to demand chess-like advance planning. And then, just like that, it's all over. The experience is over far too quickly. This is a game badly in need of an advanced mode. Bigger fields, maybe, or multiplication? It seems as though there are plenty of possibilities left to explore, so let's hope for more to come soon.

Oh, and a word to the wise. That skull and crossbones button? It does not denote deadlier levels. Instead, it very efficiently deletes your progress without any sort of verification. Probably worth avoiding that one.

So math fans and strategy nuts, enjoy. Exponential Invasion, is, as it claims, a game of mathmatical warfare, and it's a clever one. Mastering every field of battle will make for a good time, though it never takes quite enough time to fully satisfy. Still, as flaws go, it's better to be left wanting more than to become bored with what you're given, and Exponential Invasion remains compelling through its entire length.

TouchArcade Rating

  • wassupbiloxi

    Played this yesterday, and was really impressed by how clean the design is considering that the developer is in high school. That was before I tried clicking the skull-and-crossbones button, but otherwise it's pretty neat. The game could use an option to mute the sound effects, though.

    Also, is it just me, or is it impossible to do level 13 in 10 moves (the supposed minimum)? Let's bust out some graph theory: there are ten disjoint cut edges that separate a white number from all the blue numbers or a blue number from all the white numbers, and since the sum of the white numbers is the sum of the blue numbers plus the number of blue numbers, everything will be used by the end, so each of those edges needs to be traversed. That's 10 moves right there. But one of the edges (from the 2 to the 12) must be crossed twice (since the first will wipe out the blue, but you also need to move a white number into that position), so any solution must take at least 11 moves. In fact the best I can get is 17, but certainly 10 is impossible.

    • 003naveen

      I've got 3 bombs on that level. Don't remember how I did it though...

      • wassupbiloxi

        Huh. I tried it a few more times, and never solving it in fewer than 17 moves and always getting 2 bombs at the end, but now the level select menu says I've gotten 3 bombs.

      • http://twitter.com/mguniverse Danny Perski

        Shh, pay no attention to the bugs. 

        In other news, i'm fixing every problem mentioned in this review. I'm adding 12 new difficult levels, and i'm fixing the skull and crossbones button of death. Stay tuned!

      • jay401

        Thanks! It's a great little mind teaser/expander. For a one-man shop, I'm happy to pay a couple bucks for such a simple game in order to support your hobby and hopefully encourage you to continue forward with whatever other puzzle-y game ideas you might have. 🙂

Exponential Invasion Reviewed by Nissa Campbell on . Rating: 4