Old West shoot-'em up, side-scrolling, platforming action. It's not just cowboys vs indians. Heated Barrel is cowboys vs other cowboys and indians and bandits and bears and bulls and all kinds of other crap.
You are the protagonist with an itchy trigger finger. Drawn of cartoony-type early 90s graphics, you plow your way thru different western towns and scenes, inevitably facing bosses that take some time to vanquish.
The controls are simple. Along with your 8-way joystick, you have two buttons, fire and exploding barrel (bomb). You can fire in any direction (so that's good), and use the barrel bomb at any time - you turn into a barrel and explode outward, killing everything in a small radius. The number of bombs is finite but you can always collect more. The number of bombs you have left is displayed in the bottom left corner of the screen.
Power-ups are plentiful, but simple. Lots of "double-shot" and bomb power-ups. A few for increased speed and occasionally, you get a 1-up (extra life). Other stuff is infrequent.
The game has good action although is a little easy to start. The difficulty level definitely starts to increase in earnest on the 3rd level (after you defeat the bull).
There are little thoughtful touches... For instance, when some of the bosses throw grenades or dynamite at you, after they explode they turn into your power-ups. But, mostly, this is a straight-forward scrolling shooter with light, fun graphics.
A word about display, On the MAME setup I play, the default choice for aspect ratio is the typical 4:3. In many games that is not the native (correct) display for that game. In Heated Barrel, the game's actual ratio is 1:1 and by changing the display, the game gets much better looking (as you can imagine). Sometimes, graphics aren't great or look a little less than sharp and I don't always think about changing the video aspect ratio. That's a mistake.