The original arcade version of Air Rescue was a sprite-scaling version of the ancient game Choplifter, which saw you flying around in 3D rescuing very ugly soldiers from active battlefields. Though it might have been possible to make a decent job of porting it to the Mega CD, attempting to do so on the Master System would have been an act of Ozymandian hyubris. Luckily, that's not what's been attempted here, Master System Air Rescue is more like a decade-later sequel to Dan Gorlin's game.
Once again, you're in a helicopter, and once again, you're rescuing little guys. Most of the differences between this game and Choplifter are small, but there's also a lot of them, so it's a different enough experience. The controls are better: there's no longer a button to change which direction you're facing, there's a bunch of weapons to choose from, and you no longer have to sit around waiting for your rescued guys to slowly and individually disembark when you fetch them back to base.
The biggest difference is that Air Rescue has significantly more complex stage design than Choplifter. Which you'd expect, with there being a decade bewteen their respective release dates. Right from the first stage, you've got more interesting fields of engagement than Choplifter's flat battlefields. The first stage is a theme park that's been taken over by terrorists, then you're rescuing people from a burning building, a commercial airport, some sinking cruise ships, and some kind of giant underground facility. They all have their own unique feel and hazards, and it doesn't just feel like they're a bunch of hitboxes arranged into different shapes.
There is one problem, though. Every stage has terrorists shooting at you, and I guess all of the various disasters were caused by them too? I don't think the game needed that, to be honest. The disasters could just have been disasters, and danger could have been added through gradual escalation of the disasters: boats sinking with civilians still on them, explosions in the burning building, and so on. Maybe all this stuff would have been a little out of reach for the Master System? The game does look great generally, and it was ancient hardware in 1992, so it's likely they were already pushing it as hard as it could go? Still, the constant presence of the terrorists feels a little silly, and I think it would have been better to keep them as a final stage thing. Like "you saved people from passive disasters, but now you have to rescue them from an actively hostile threat!", you know?
Despite its shortcomings, I've enjoyed playing Air Rescue. It's a decent enough implementation of a classic concept. It's nothing special or life-changing or anything, but it's not bad, either. It is pretty unforgiving, though, so be prepared to have a little patience when you first start playing.