Raptor is one of the few vertically scrolling shooters specifically designed for the PC, and includes all of the features you would expect as a result (save/load, a weapon shop, and controller configuration). Mouse, keyboad, joystick and joypad are all handled well. This 2010 release is a Windows binary and almost identical to the original, but features an options dialog which allows you select your input method, and to increase the native resolution of the game using scalers and filters (similar to how DOSBOX works).
The variety of enemies throughout each episode is just enough to prevent them from getting boring, and as the levels go on, their attacks get increasingly devastating. Most enemies shoot directly forward, and the emphasis of gameplay is in avoiding front-on attacks, sneaking in your kills between pauses in enemy fire. Bosses are well designed with strict firing patterns, and planning your attack will allow you to win you each level with minimal damage.
The most exciting feature of most PC shooters, the weapons shop, is unfortunately my biggest disappointment with Raptor. There are very few modestly priced upgrades after the first 3-4 levels of gameplay, and the more expensive weapons can turn a difficult level into a walk in the park. It can be difficult to find a weapon that allows you to balance your skill with the enjoyment of the game.