The 1985 game of the year is Super Mario Bros.
The runner up is Tetris.
The master thread for all of these contests can be found here.

What do you believe to be the "Game of the Year" for 1985 and why?  Also, vote on "Game of the Year" for 1985. 

Gauntlet (Arcade)
Atari makes another hit arcade game with Gauntlet.  It should be noted that at this point in time, Atari, creator of the video game industry, takes on a different type of role in gaming history.  In 1984 Atari split into two companies: Atari Corporation, focusing on computer games and future Atari consoles like the Jaguar and Lynx, and Atari Games, maker of hit arcade games like Gauntlet.  Whenever Atari Games (maker of Gauntlet) wanted to make a console game, then they went by the name Tengen.  Gauntlet was one of only three licensed games that Tengen made for the NES.  Then they went rogue and made a whole bunch of unlicensed games.

Gradius (Arcade)
This first game in Konami’s long running series was an arcade hit.  The port to the NES also did well selling over 1 million copies.  While developing the NES port of Gradius, one of the developers found the game to be too hard and so put a secret code in the game so that they could start with all power ups and options.  This code was up, up, down, down, left, right, left, right, B, A, START.  

Paperboy (Arcade)
Atari Games has another arcade hit in 1985 with Paperboy.  Paperboy was also ported to many, many computer and console systems.

Space Harrier (Arcade)
Sega developed an arcade hit with this 3D on-rails shooter.  It was ported to the Sega Master System in 1986 and eventually to many other systems including the Famicom.

Tetris (Electronika 60)
This history of Tetris has so many twists and turns that they could make a movie about it (and they did).  However, the first version was made by Alexey Pajitnov in 1985.  One story probably not mentioned in the movie is that Atari Games made the arcade version of Tetris in 1988 and therefore Tengen ported it to the NES (unlicensed) in 1989.  Shortly thereafter Nintendo secured the home console rights to Tetris from the USSR government, and Tengen had to remove it’s version of Tetris from store shelves.  Only about 100,000 copies of the Tengen Tetris were sold (and it is often considered the superior version).  However, the Nintendo published version sold over 8 million copies on the NES.  Tetris was also commonly bundled with the Gameboy and was considered key to the Gameboy’s success.  This version sold over 35 million copies.  Counting all versions, across all platforms, Tetris has sold over 520 million copies.

The Bard’s Tale (Home Computers)
The Bard’s Tale was the most successful computer RPG of the 80’s.  By 1993 over 1 million copies of the game had been sold.

Ultima IV: Quest of the Avatar (Apple II/C64)
While Ultima III resembles almost every JRPG, Ultima IV is one of a kind.  Instead of trying to save the world, the quest is to perfect yourself and become the Avatar, the pinnacle of virtue.  Often considered the best CRPG of the 80’s and also commonly lands on “Best computer games of all time” lists.  Ultima IV was also commercially successful selling over 400,000 copies by 1989.

Where in the World Is Carmen Sandiago? (Home Computers)
Carmen Sandiago was designed to be edutainment, but it ended up being treated that way, since it taught players a whole lot about geography.  Carmen Sandiago became a hugely popular computer game by 80’s era standards, selling over 4 million copies by 1995.  It also became a cultural phenomenon spawning multiple different TV shows.

TV Intro: https://www.youtube.com/watch?v=ToWuQSpROw0
Game Show Intro: https://www.youtube.com/watch?v=-TL5-u3ey-c

Super Mario Bros.  (NES)
This hidden gem was designed by Shigeru Miyamoto.  Koji Kondo composed the music and Takashi Tezuka was a co-designer.  Super Mario Bros was the main killer app for the NES, the system that started home console gaming in Japan and revived the console market in North America.  Super Mario Bros was commonly bundled with the system, selling over 40 million copies on the NES alone.

TV Show Intro:  https://www.youtube.com/watch?v=Tv6uqCjggMA

Other (please specify)
If you think another games deserves to be "Game of the Year" other than one of the 9 I listed above, then please vote “Other” and say your game in the comments.  If the "Other" category takes at least 2nd place and no other game gets at least 50% of the vote, then I will do a runoff vote including the most mentioned game(s) from the comments.

The winner of this vote will be decided Saturday, Sept 16 at 11:59 EST.

Here were some other notable releases in 1985:

Ghosts and Goblins (Arcade)
Hang On (Arcade)
Indiana Jones and the Temple of Doom (Arcade)
Phantasie (Home Computers)
Winter Games (Home Computers)
Chaos (Home Computers)
King's Quest 2 (Home Computers)

Whoever uploaded that Paperboy video literally made the exact same mistake three times in a row right at the start xD

Getting closer to my birth date now, so I've actually played a few of these, but none I love. I'll narrowly give my vote to Tetris.

Hard not to choose Super Mario Bros - though I think Space Harrier has the better music and Bard's Tale (though somewhat underwhelming in retrospect) had a big influence on future RPGs - especially Might & Magic

It's Mario.
A revolutionary game that still holds up as a mechanical masterpiece nearly 40 years later.
Tight controls, elegant level design, tons of content by the standards of its time, and polished to a dazzling sheen.

I think the choice here comes between Tetris and Super Mario Bros. The others may be influential in their own right, but I don't think it can really be argued that the two games with the most far reaching impact form that list are those two. I think the same holds true for how well the games have aged.

I can't believe that Gauntlet in the arcade came out the same year as Super Mario Bros. Granted, I didn't actually play SMB until over a year later, but it's mind boggling how time seemed to pass sooo much slower when we were young.

Anyhow, the impact of SMB and Tetris speaks for itself but it's definitely Mario for me. I played it for the first time in an arcade on one of Nintendo's Play Choice machines and I couldn't stop thinking about playing it again, just like SMW and SM64 several years later. Between this and those weird Zelda commercials, I knew I wanted an NES for sure.

Some fun games here like Tetris and Paperboy, but my personal runner up would be Space Harrier. Playing that for the first time in an arcade on the sit-down, full-motion unit was amazing. Loved Sega's arcade games.

Voted Gradius.

This was the year that I feel gaming took a real step forward. TwinBee was my first ever multiplayer game. Gradius was like the coolest thing ever (I liked some sequels and Salamander more but it marked the start of one of my favorite series of all time). Super Mario Bros is self explanatory, too bad I didn't have a NES and barely played it. Other games I enjoyed include Castle Excellent (The repetitive music may give you a serious headache. But I loved the game on MSX, probably my first difficult puzzle game) and King's Valley.

And yet 1986 and 1987 were notably better from what I remember.

This was a good year, and I'd say the first year of released where I'd have considered myself a video gamer. Although, I probably played many of these 2-3 years after this. Super Mario Bros was a game that I played to death as a kid - like over and over and over again.

For the record, the rumour where I grew up was that you had to finish the game 100 times to see the princess naked... man, us 80s kids were all perverted.

My personal favourites from that year are Bard's Tale and Ultima IV - but that's in retrospect.
Games I actually played the most from '85 are Ghost'n'Goblins, Gauntlet, The Way of the Exploding Fist, Commando and Daley Thompson's Decathlon.

I honestly never cared much for SMB, scrolling platforming never really appealed to me, as opposed to exploration based platforming of games from that era.
I voted for Tetris, though I was also never really much into it.