Rolling Thunder 2 is an arcade title at its core. This helps explain why it's hard as hell. In fact, it's unforgiving. In some areas your timing and strategy have to be quite precise. But I'm getting ahead of myself...
You play as either Albatross or Leila, international government agents, attempting to figure out the relationship between communications satellites being shot down, world unrest, and a terrorist organization which bears a striking resemblance to the Geldra organization Albatross brought down in the 60's in the process of rescuing Leila. Funny, neither of them appear 20 or so years older... Anyway, the story is really just trappings for an arcade-style game. Leila and Albatross play identically so who you pick is really down to aesthetics.
Just like the original Rolling Thunder, you walk, jump, crouch, and shoot through several levels. You can shoot while standing or crouched but not when jumping. You can jump normally or you can hold up when you jump to either jump really high straight up. If you are under a platform with a railing you can high-jump up onto the upper platform. Holding down and hitting jump makes you jump down to the level below. The game play of the game is based heavily around jumping up and down between the upper and lower levels of stages and interacting with enemies in both locations. Unlike the first game, you don't get hurt by bumping into enemies, though both of you do bounce back from the collision. You do get hurt from being punched, shot, or exploded by grenades.
The game also features the return of doors. Enemies will emerge from doors and you can enter doors just as they can. Hold up in front of a door and you enter it. Hold up and you can remain behind the door, where enemies can't hurt you. Some doors are marked and give you more handgun ammo or machine gun ammo. See, you start each level with 40 bullets in your handgun. When you run out you can only fire a single, slow bullet at a time. Entering a machine gun room gives you anywhere from 40 - 80 shots of machine gun fire. You automatically switch back to your pistol when the machine gun shots run out. Sometimes a life restore/increase or a time increase is hidden behind an unmarked door, so it can be worth it to duck into random doorways. There are also arches and alcoves you can slip into, much like doors, only you pop in and out more quickly. Basically, you duck in and out of the corner in between getting shot at
This game is very conducive of slow, careful advances. There are lots of enemies to deal with and some of them will come out of doors right after you pass by. They will come from in front, behind, even up through the floor and from chutes. You have to be careful how much you dally, though, because there's a timer on each level. If you don't reach the exit in time you die, so learn where the time extensions are or get very good at moving ahead despite being swarmed by baddies.
The graphics in this game are pretty good. They're not as good as the arcade, naturally, but they're close. There are some problems, though. In the arcade you can tell which baddies can and can't throw grenades and how many hits it'll take to kill them based on the sprite design and color scheme. The Genesis has good distinction on how many hits enemies take, but it's hard to tell who can and can't lob a grenade at you. This is a shame, because grenades are faster and harder to avoid than bullets. The audio and music are pretty good, relatively faithfully recreated on the Genesis.
The Genesis does have one advantage over the arcade. It features unlimited continues and a password system to resume where you left off (at the beginning of the level, anyway.) It also has several extra levels. In fact, every other level is new, for a total of 11 levels. There are also a couple bosses thrown in, a couple new weapons (laser and flamethrower), and even the last boss has a new twist.
One area in which the Genesis Rolling Thunder 2 is very close to the arcade, and in fact the original Rolling Thunder, is the challenge level. This game is hard. It will eat you alive. It's cursing-out-loud hard. I know, because I did. My wife had to hide in the other room until I calmed down. The thing is, it's also good about giving you that feeling that if you were just paying slightly better attention or hadn't scratched that itch at an inopportune time you'd have almost had it. The learning curve is steep but it is a curve. You'll get stuck on a level for a half hour and be so angry you have to walk away. But the next day, when you foolishly sit down to play again you'll finally have the calm to advance another two levels before getting stuck again. The game's like an addiction, only less life-affecting and ultimately more positive. Oh, and when you finally do win you get a password to tackle the game all over again in hard mode. Hah! Sucker...
This game is not for lightweights. This is an ironic statement because I'm a lightweight, so maybe it is for the right lightweights. If you want an arcade-style action game which demands practice and refinement, which you can, thanks to the password system, pick up and put back down, this is the game. It will kick your ass, but with a little patience and practice you'll kick back. And when you're done you'll feel like you have something to brag about.
*disclaimer* I am not cool enough to beat this game on hard (or rather, I value my blood pressure too much to try). I beat it on normal and was so damn proud of myself when I finally got to the end. And you should be, too, if you're game.