Exponential Invasion sounds like it's going to resemble either ZiGGURAT or a Masters degree in stochastics.
Inspired as it is by Sudoko and chess, Exponential Invasion is learnt by playing. The tutorial is built into the first five levels - once you're done with those, you know the basics of how the game works.
The rules are easily grasped. Numbers can only move to their neighbouring squares. If they move onto another number and the number that moves is bigger, they add together. You have to remove all the highlighted numbers to complete the level.
Nothing could be simpler.
I've got logarithimOf course, just having the tools at your fingertips isn't enough to finish a level. Sometimes you blunder into numerical cul-de-sacs. Other times you complete levels only to be told that the perfect number of steps is lower than the number you managed to do them in.
There are niggles. I would like to have known that the cool-looking skull & crossbones button wiped all my data and highscores before I pressed it - or certainly let me know at some point instead of just wiping it immediately.
And Exponential Invasion is missing all but the most basic features - at the very least I want to see how I'm doing against friends on Game Center.
The visuals are stylish, but also a bit too minimalistic. The language it uses - invasion, towers, and so forth - is so colourful compared to the actual black and white box-ticking game.
The fog on the Sine
It's also rather short. This app should have hundreds of levels - like Frederick Raynal's so-so puzzler bOxOn - rather than a measly handful that you'll rattle through in no time.
It also doesn't explore nearly enough of the possibilities available with the ruleset - there could have been puzzles that don't use all the numbers, puzzles that don't add up perfectly, challenge missions that have only one solution, and so on.
Exponential Invasion is a solid, fun mechanic in search of more content. A hardened Sudoko player or maths bod will breeze through the 20+ levels available in under 30 minutes, which isn't great for $2. But given a little love, and more levels, we can see this experiencing explosive growth.