Dishonored might remind you of some video games of the past, but when it comes down to it, you probably haven’t seen anything exactly like it. That’s the refreshing thing about the first-person action game where you play a supernatural assassin in a Victorian steampunk metropolis known as Dunwall.

Dishonored is a relatively rare thing these days since it is a major original title from a big video game studio, the Arkane Studios division of ZeniMax Media. ZeniMax’s Bethesda Softworks will publish it. The title bears some resemblance to Assassin’s Creed, and it offers a wide array of weapons such as those found in the BioShock series. Its sci-fi fantasy world and gameplay might remind you of BioShock, Deus Ex, Thief, Dark Messiah, or Blade Runner, but it’s not a copycat of any of those works.

You start the game as the once-trusted bodyguard of the Empress of the land, but now you stand accused of her murder. You believe you’ve been framed, and revenge is your objective. You become an assassin, wearing a disturbing mask as your calling card. You move through the world of Dunwall, which plague has besieged and a corrupt government has run down.

The combat system allows you to play in stealth mode, stealing lives like a thief. Or you can fight in the open. If you choose the latter, the guards of the city will descend upon you and take you out. As you pursue each mission, you pick up clues about your alleged betrayal.

Each mission offers a whole set of challenges, and you can solve them any way you want. The gameplay encourages player creativity. For instance, you can use your supernatural power to possess the spirit of a fish. You can then swim into an open grate in the moat of a castle. Once you are inside, you can transform into a rat and then move further. You can sneak past the guards and eavesdrop on conversations to identify where your assassination targets might be. Then you can take out your targets with knives or guns in a most gruesome way.

“It’s a game about an assassin that you can literally play without killing anyone,” said Harvey Smith, co-creative director at Arkane Studios, in a recent demo of the game in San Francisco, Calif.”Every step of the way feels like you are crafting your own game design experience.”

The game is set in an 1850s alternate reality that resembles a Londonesque whaling city, but it’s not really London, Smith said. Bodies from the plague line the streets. The environment is gray and dark and full of cockroaches. The art is stylized — beautiful but not realistic. The 3D graphics look superb, and the game makes plenty of use of shadows, lighting, effects such as fog and search lights, and it has dark mood music.

There are hyena-like dogs that look like nothing you’ve ever seen.

I saw a mission where you infiltrate a castle partway through the game. If you perform well, you affect the next mission. For example, you might start on rooftops, where you have an advantage, said Raphael Colantonio, co-creative director at Arkane Studios.

When you get inside the castle, you have to find two politicians to kill. You can use a supernatural power dubbed a “blink” that allows you to cross a short distance practically instantly, evading the eyes of guards. But you have to spend energy on your powers, so you can’t use them all the time. You can explore upward into buildings and climb on the outside of walls to get around obstacles. If you find objects called runes, you can gain more powers.

The mission changes the locations of your targets every time you try it, so you can replay them as much as you want in a different way each time. Sound propagates through materials; conversations heard through a keyhole in a door will be muffled, for instance. You can blow out a candle, and a guard might comment that he can’t see anything. When you catch a politician with his woman in the steam room, you can lock them in and turn up the heat, killing them with the steam. Or you can plant a gadget known as a spring mine, which pops up in the air and then shoots spikes out.

As with Assassin’s Creed, you can drop from above and take someone out with a knife. You have a brief window of surprise to do so before they start yelling or fighting back. Guards will notice when a patrol route has been vacated because you’ve killed one of the soldiers.

If you don’t want to kill someone, you can wipe the person’s memory and sell them into slavery instead, effectively eliminating them. Once you are spotted, you can short-teleport out via the blink feature. And if you jump out of the castle, you can change into something that will survive the fall. But if the animal you are possessing dies, you’ll die as well.

In another level, the developers showed how guards can walk around on big mechanical contraptions (pictured above) and chase you down. They can shoot fire arrows at you, but you can shove them back using a power known as Wind Blast, which will reverse the arrow and send it in the opposite direction.

The game uses Epic’s Unreal Engine for its graphics technology. Dishonored will come out in 2012 on the Xbox 360, PlayStation 3, and the PC.