An unforgiving difficulty level and damaging slowdown problems make this a real masochist's dream.
You start off as a slow-moving ship - the R-Type "Arrowhead" of the title - and your only real weapon is to charge the cannon for a huge laser blast. Enemies attack in waves, and until you are able to acquire power-ups that can make you faster, you're pretty much up against it. Fortunately, you can acquire the "Force", an indestructible orb that can destroy anything it touches including enemy shots - or so the game would have you believe.
The Force does make things easier but unfortunately, a big laser blast from a boss or even an out of control enemy you've shot can pass through the Force and destroy you. Coupled with the fact that contact with ANYTHING results in an instant kill, and the fact there are no checkpoints and no way to retain the Force or any power-ups you've got, this makes the game unbelievably frustrating.
The sheer number of enemies on screen at times makes for severe slow-down issues and although some state that this actually makes it easier to see what's happening, it tends to frustrate even more as you can't move as freely as you want to. Often, when the slow-down ceases unexpectedly, you'll find yourself in more trouble than you were already.
The power-ups are a mixed bunch. The shotgun-bomb is very handy and destructive, but only available from the 4th level, whereas the spread laser and rebound laser can be useful or frustrating in terms of accuracy. Your ship can be powered-up to the nines with the Force, an automatic missile drop, and two Bits, floating orbs that are above and below the ship and act in much the same way as the Force. The problem is these are annoyingly infrequent and require getting past some unpleasant obstacles before they're available - in other words, you get them after you needed them most.
Graphically the game suffers from slowdown owing to the surprisingly detailed levels, waves of aliens and sheer amount of action happening, and the soundtrack is impressive even by Snes standards. Sadly, these are highlights in an otherwise badly flawed game.
R-Type would've been a lot more fun were it actually beatable, instead it requires a perfect playthrough from the start, infinite patience and not having anything else to do to make it worth the effort of trying.