99Bullets looks like a scrolling shooter. It plays like a shooter. But, as new players will find out to their cost, applying the rules ingrained in your mind from all the countless shooters you've played before is the surest route to failure.
You control a robot with a numerical tally in its stomach – in each level you have 99 bullets to shoot, and a (challenging) score target to hit before moving onwards. One bullet can kill multiple enemies, and the robot can move across both screens while firing up, down, left or right: whizzing around while spamming shots into enemies works in the initial stages, but soon 99bullets becomes a different game entirely.
That game's a Simon Says shooter, in which every level has a pattern and an optimum way to use those precious bullets. As you progress, level layouts and the objects within them become more surprising, eschewing cannon fodder in favour of obstacle courses. It never reaches a stage where one or two missed shots ruin things, but maximising your limited payload is essential. Taking a hit doesn't kill your robot. Rather, it reduces your bullet count by one, a touch that initially seems generous but quickly proves dastardly.
99bullets is about learning rather than doing: each run-through of arcade mode starts at the first level, so replaying layouts and learning to perfect them is the cornerstone of its design. There is a level select to practice any previously completed stage, but this could have done with something smarter – a randomly generated endless mode, or at least some online leaderboards. As it is, 99Bullets is a smart idea, executed in a very controlled fashion, but could do with letting its hair down occasionally.