The control of the ships in Defender is pretty responsive. There are a few different ship classes, some of which sacrifice some speed or maneuverability for armor or firepower, and so on. Generally, you'll be able to move forward at high speeds and slowly in reverse. You automatically pick up humanoids by flying close to them, and you won't ever run into the ground, even if you dive directly at it. This means you can get pretty fancy with the flying, swooping down at full speed, picking up some humanoids, and getting away before the landers can draw a bead on you. The right analog stick serves as a stunt control, allowing you to execute barrel rolls, loops, and quick 180-degree turns. You'll earn credits as you move through the game, and they can be used to purchase different weapons for your ship or, in an attempt to make the game feel similar to the arcade classic, extra lives. You can toggle through the different weapons with the touch of a button. The game's higher-end weapons are pretty powerful, but your basic blaster does a good job, provided your aim is steady.
Visually, Defender does just fine. The environments look convincingly like wastelands with small human outposts on them, and the game runs at a smooth frame rate. The design of the enemy ships actually evokes that of the classic 2D arcade equivalents, which is a nice touch. The game can also put a lot of enemies onscreen at one time without dropping frames, which is a suitable trade-off for the lack of sheer complexity in the graphics.
The remake of Defender is focused on making you complete various in-level objectives.
The game's sound is decent. The voices used for game briefings and in-mission orders are pretty good. The effect used for the ship's main blaster does a suitable job of emulating the effect used for the original Defender's blaster, though the rest of the game's weapons sound pretty unfulfilling. Additionally, there's one simple mistake that only fans of the original game will notice or care about. When a lander abducts a humanoid, it makes a sound from the original Defender--it just doesn't make the right sound from the original game. The sound it makes sounds more like the sound that swarmers make when they fire at your ship than the proper human abduction noise. It's nothing that breaks the game or anything, but it's one of those weird mistakes that will be difficult for fans of the classic game to fathom.
If you like mission-based space combat simulations such as Wing Commander, and you don't mind the game's defensive focus, Defender does a mostly good job of walking the line between having modern gameplay depth and remaining somewhat faithful to the source material. Nevertheless, fans of the genre or of the original game would be better off renting this one first, as it doesn't really go too far out of its way to distinguish itself.