Look.............

 1981

• Donkey Kong (Arcade) - North America and Japan release

 1982

• Donkey Kong (Game & Watch) - North America and Japan release
• Donkey Kong Jr. (Game & Watch) - North America and Japan release

 1983

• Mario Bros. (Arcade) - North America and Japan release
• Mario's Bombs Away (Game & Watch) - North America and Japan release
• Mario's Cement Factory (Game & Watch) - North America and Japan release

 1984

• Golf (Famicom) - Japan release - Mario is the main character.
• Pinball (Famicom/NES) - North America and Japan release - Mario is found in the bonus stage.
• Punch Ball Mario Bros. (NEC PC-8801) - Japan release
• Punch-Out!! (Arcade) - North America and Japan release - Mario is the referee.
• Tennis (Famicom) - Japan release - Mario is the referee.

 1985

• Super Mario Bros. (Famicom/NES) - North America and Japan release
• Wrecking Crew (Famicom/NES) - North America and Japan release - Mario is the main character.
• Tennis (NES) - North America and Europe release - Mario is the referee.

 1986

• All Night Nippon Super Mario Bros. (Famicom Disk System) - Japan release
• Golf (Famicom Disk System) - Japan release - Mario is the main character.
• Golf (NES) - North America and Europe release - Mario is the main character.
• Super Mario Bros. (Famicom Disk System) - Japan release
• Super Mario Bros. 2 (Famicom Disk System) - Japan release
• Super Mario Bros. Special (NEC PC-8801) - Japan release
• Vs. Super Mario Bros. (Arcade) - North America and Japan release
• Tennis (NES) - North America and Europe release - Mario is the main character.

1987

• Wrecking Crew (NES) - Europe release - Mario is the main character.

 1988

• Donkey Kong (Atari 7800) - North America and Europe release
• Donkey Kong (Famicom Disk System) - Japan release
• Donkey Kong Classics (NES) - North America release
• Donkey Kong Jr. (Atari 7800) - North America and Europe release
• Donkey Kong Jr. (Famicom Disk System) - Japan release
• Famicom Grand Prix II: 3D Hot Rally (Famicom Disk System) - Japan release - Mario and Luigi are playable characters.
• Kaettekita Mario Bros. (Famicom Disk System) - Japan release
• Mario Bros. (Atari 7800, XEGS)
• Super Mario Bros. (Wristwatch Game) - North America release
• Super Mario Bros. 2 (NES) - North America release
• Super Mario Bros. 3 (Famicom) - Japanese release
• Super Mario Bros./Duck Hunt (NES) - North America release

 1989

• Alleyway (Game Boy) - North America and Japan release - Mario appears in bonus level, also drives/flies/controls the paddle on screen as shown in the intro
• Donkey Kong 2 (Game & Watch) - North America and Japan release
• Donkey Kong Classics (NES) - Europe release
• Super Mario Bros. 2 (NES) - Europe and Australia release
• Super Mario Land (Game Boy) - North America and Japan release
• Tetris (Famicom/NES) - North America and Japan release - Once player beats Level 9 Height 5, Mario and friends appear.
• Tetris (Game Boy) - North America and Japan release - Mario and Luigi appear in 2-player game.

 1990

• 3-in-1 Super Mario Bros./Duck Hunt/World Class Track Meet (NES) - North America release
• Dr. Mario (Game Boy)
• Dr. Mario (NES)
• F-1 Race (Game Boy) - North America, Europe and Japan release - Mario appears when player wins a race, waving the checkered flag and congratulating him.
• Punch-Out!! Featuring Mr. Dream (Famicom/NES) - North America, Europe and Japan release - Mario is the referee.
• Super Mario Bros. 3 (NES) - North America release
• Super Mario Land (Game Boy) - Europe release
• Super Mario World (Super Famicom) - Japan release
• VS. Dr. Mario (Arcade) - North America and Japan release

 1991

• Mario the Juggler (Game & Watch) - North America and Japan release
• Mario Teaches Typing ([[MS-DOS]) - North America release
• Super Mario Bros. 3 (NES) - Europe release
• Super Mario World (SNES) - North America release
• NES Open Tournament Golf (NES) - North America release
• Super Mario Bros. & Friends: When I Grow Up (PC) - North America release
• SimCity (Super Famicom/SNES) - North America and Japan release - A Mario statue is awarded once a Megalopolis level of 500,000 inhabitants is reached
• The Legend of Zelda: A Link to the Past (Super Famicom) - Japan release - Mario is depicted in several portraits in Kakariko Village.
• Yoshi (Famicom) - Japan release
• Yoshi (Game Boy) - Japan release

 1992

• Super Scope 6 (SNES) Mario flies by in a plane whenever the player reaches a certain point in the "Intercept" portion of LazerBlazer.
• Super Mario USA AKA Super Mario Bros 2 (Famicom) - Japan release of Super Mario Bros. 2
• Super Mario Kart (Super Famicom/SNES)
• Yoshi (Famicom/NES, Game Boy) The player controls Mario or Luigi
• Yoshi's Cookie (Famicom and Game Boy) - Japan Release
• Mario Paint (SNES)
• Super Mario Land 2: 6 Golden Coins (Game Boy)
• Mario's Time Machine (DOS)
• Super Mario World (SNES) - Europe release
• Mario Is Missing! (DOS) Mario is captured by an unidentified green Koopa-like creature
• SimCity (SNES) - European Release - A Mario statue awarded once a Megalopolis level of 500,000 inhabitants is reached
• The Legend of Zelda: A Link to the Past (SNES) - US release - Mario is depicted in several portraits in Kakariko Village.

 1993

• Mario Is Missing! (SNES, NES, PC)
• Mario's Time Machine (SNES)
• Mario and Wario (Super Famicom) - Japan only
• Super Mario All-Stars (Super Famicom/SNES)
• Yoshi's Cookie (NES, SNES, Super Famicon and Game Boy) - North America and Japan release
• Mario's Early Years! Fun with Letters (SNES) - North America only
• Mario's Early Years! Fun with Numbers (SNES) - North America only
• Mario's Early Years! Preschool Fun (SNES) - North America only
• Yoshi's Safari (SNES/Super Famicon)

 1994

• Manhole (Game & Watch)
• Donkey Kong '94 (Game Boy)
• Wario Land: Super Mario Land 3 (Game Boy) Mario makes a very small cameo at the end
• Tetris & Dr. Mario (SNES)
• Super Mario All-Stars & World(Super Famicom/SNES) - Japan, North American, and Europe
• Mario's Time Machine (NES) - North America only
• Yoshi's Cookie (NES) - Europe Release
• Hotel Mario (CD-i)

1995

• Mario's Tennis (Virtual Boy)
• Mario Teaches Typing (Microsoft Windows)
• Mario Teaches Typing (Macintosh)
• Mario Clash (Virtual Boy)
• Mario's Picross (Game Boy)
• Mario's Picross 2 (Game Boy)
• Mario's Super Picross (Super Famicom) - Japan only
• Undake 30 Same Game (Super Famicom Satellaview) - Japan only
• Mario Excite Bike (Super Famicom Satellaview) - Japan only
• BS Dr. Mario (Super Famicom Satellaview) - Japan only
• BS Super Mario Bros. 3 (Super Famicom Satellaview) - Japan only
• Mario's Game Gallery (PC)
• Super Mario World 2: Yoshi's Island (SNES)
• Donkey Kong Country 2: Diddy's Kong Quest (SNES)

 1996

• Super Mario RPG: Legend of the Seven Stars (Super Famicom/SNES)
• Super Mario 64 (Nintendo 64)
• Mario's Picross 2 (Game Boy) - Japan only
• Mario Teaches Typing 2 (PC)

 1997

• Game & Watch Gallery (Game Boy)
• Game & Watch Gallery 2 (Game Boy)
• Mario Kart 64 (Nintendo 64)
• Mario Teaches Typing 2 (PC)
• Mario's FUNdamentals (PC)

 1998

• Mario no Photopi (Nintendo 64) - Japan only
• Wrecking Crew '98 (Super Famicom) - Japan only
• Mario Party (Nintendo 64) - Japan release
• The Legend of Zelda: Ocarina of Time (Nintendo 64) - Painting in Hyrule Castle

 1999

• Super Mario Bros. Deluxe (Game Boy Color)
• Game & Watch Gallery 3 (Game Boy Color)
• Mario Golf (Game Boy Color, Nintendo 64) - (Game Boy Color) Japan Release
• Super Smash Bros. (Nintendo 64)
• Mario Party (Nintendo 64) - release outside Japan
• Mario Party 2 (Nintendo 64) - Japan release
• Mario Artist: Paint Studio (1999) Japan only

 2000

• Mario Golf (Game Boy Color) (Game Boy Color) - North America release
• Mario Tennis (Nintendo 64)
• Mario Tennis (Game Boy Color) - Japan release
• Mario Party 2 (Nintendo 64) - release outside Japan
• Mario Party 3 (Nintendo 64) - Japan release
• Game & Watch Gallery 3 (Game Boy Color) - European release
• Mario Artist: Talent Studio - Japan only
• Mario Artist: Communication Kit - Japan only
• Mario Artist: Polygon Studio - Japan only

2001

• Mario Tennis (Game Boy Color) - release outside Japan
• Paper Mario (Nintendo 64)
• Mario Party 3 (Nintendo 64) - release outside Japan
• Mario Kart Super Circuit (Game Boy Advance)
• Super Mario Advance (Game Boy Advance)
• Luigi's Mansion (GameCube)
• Dr. Mario 64 (Nintendo 64) - Japan Release - included Mario Bros. mini game

 2002

• Super Mario World: Super Mario Advance 2 (Game Boy Advance)
• Super Mario Sunshine (GameCube)
• Mario Party 4 (GameCube)
• Super Smash Bros. Melee (GameCube)
• Game & Watch Gallery 4 (Game Boy Advance)
• Animal Crossing (Gamecube) - North American Release - included Mario Bros. mini game
• Yoshi's Island: Super Mario Advance 3 (Game Boy Advance)

2003

• Super Mario Advance 4: Super Mario Bros. 3 (Game Boy Advance)
• Mario Party 5 (GameCube)
• Mario Kart: Double Dash!! (GameCube)
• Mario & Luigi: Superstar Saga (Game Boy Advance)
• Mario Golf: Toadstool Tour (GameCube)
• Animal Crossing (Gamecube) - Australian Release - included Mario Bros. mini game
• WarioWare, Inc. Apppeared in some of the MicroGames
• Nintendo Puzzle Collection (GameCube) - Japan only - Dr. Mario is a game in the collection

 2004

• Super Mario Fushigi no Korokoro Party (Arcade)
• Mario vs. Donkey Kong (Game Boy Advance)
• Mario Golf: Advance Tour (Game Boy Advance)
• Super Mario Bros. (Classic NES Series) (Game Boy Advance e-Reader)
• Paper Mario: The Thousand-Year Door (GameCube) Sequel to Paper Mario.
• Mario Pinball Land (Game Boy Advance)
• Dr. Mario (Classic NES Series) (Game Boy Advance)
• Mario Power Tennis (GameCube)
• Super Mario 64 DS (Nintendo DS)
• Mario Party 6 (GameCube)
• Animal Crossing (Gamecube) - European release - included Mario Bros. mini game
• Wrecking Crew (Game Boy Advance)
• Super Mario Bros.: The Lost Levels (GBA} - Japan only
• Metal Gear Solid: The Twin Snakes (GameCube) Figurine of Mario along with Yoshi on a computer console after the first fight with Grey Fox.
• Pokemon Leaf Green and Pokemon Fire Red when you go into the mimic's room. If you examine the NES, it says " Mario has a bucket on his head ".

 2005

• Mario Power Tennis (GameCube) - European Release
• Mario Party Advance (Game Boy Advance)
• Dr. Mario & Puzzle League (Game Boy Advance)
• Mario Superstar Baseball (GameCube)
• Dance Dance Revolution: Mario Mix (GameCube)
• Super Mario 64 DS (Nintendo DS) - Australia and Europe Release
• Mario Party 6 (GameCube) - Australia and Europe Release
• Super Princess Peach (Nintendo DS) - Japan release
• Mario Party 7 (GameCube)
• Mario Kart DS (Nintendo DS)
• Mario Tennis: Power Tour (Game Boy Advance)
• Mario & Luigi: Partners in Time (Nintendo DS)
• Super Mario Strikers (GameCube)
• Mario Kart Arcade GP (Arcade) -international release-
• NBA Street V3 (GameCube) Nintendo All Stars Team
• SSX On Tour (GameCube) Mario is a playable snowboarder
• Yoshi Touch & Go (Nintendo DS)

 2006

• Mario Party 7 (GameCube) - European and Australia Release
• Mario & Luigi: Partners in Time (Nintendo DS) - European and Australia Release
• Super Mario 64 DS (Nintendo DS) - Chinese release
• Super Princess Peach (Nintendo DS) - release outside of Japan
• New Super Mario Bros. (Nintendo DS) playable character
• Mario Hoops 3-on-3 (Nintendo DS) playable character
• Mario vs. Donkey Kong 2: March of the Minis (Nintendo DS) supporting character
• Yoshi's Island DS - (Nintendo DS)- supporting character
• WarioWare: Smooth Moves - December 2 (Wii) - Japanese release - Appears in minigames

 2007

• WarioWare: Smooth Moves (Wii) - North American release - Appears in minigames
• Super Paper Mario (Wii) April 9, 2007
• Mario Party 8 - (Wii) - May 29, 2007
• Itadaki Street DS (Nintendo DS) - June 21, 2007 (Japan)
• Mario Strikers Charged (Wii) - July 30, 2007
• Mario & Sonic at the Olympic Games (Wii, Nintendo DS) - Holiday 2007
• Super Smash Bros. Brawl (Wii) - TBA 2007
• Super Mario Galaxy (Wii) - TBA 2007

Is Mario in Warioware: Smooth Moves? I don't remember seeing him. Also, you have it listed twice (so I'm sure there are others listed twice, just don't feel like looking).

 -edit-

He also appears in Brain Age (in the connect the lines game) and Big Brain Academy: Wii Degree in the spot the picture game. 

We need more Mario games!

IDK.

Ahhh, Hotel Mario. Nintendo at one time owned a chain of "love hotels" (back in the 1950's or so if memory serves) and I always like to think of Mario and Luigi scurrying about to keep the sheets changed and the condom dispensers filled as guests rent by the hour. Never played the 1994 CD-i game, this is just what I always think it must be like. >:)

counting games multiple times cause they were released in different parts of the world at different times is stupid. Also, unless they are significantly different, multi-platform should only be counted once. This list should be cut easily in half or even down to a quarter of the size.

Also, Mario/Duck hunt/track and field is placed in '90 when it was released in '88 according to the linked wikipedia entry (plus i got it in '89).

Mario teaches typing was the best typing game ever, to bad i can't find it anywhere. I used to have a copy on floppy but it went bad.