A mobile game is a video game played on a mobile phone, smartphone, PDA, handheld computer or portable media player. This does not include games played on handheld video game systems such as PlayStation Portable or Nintendo DS.

The first game that was pre-installed onto a mobile phone was Snake on selected Nokia models in 1997. Snake and its variants have since become the most-played videogame on the planet, with over a billion people having played the game.

Mobile games are played using the technologies present on the device itself. For networked games, there are various technologies in common use. Examples include text message (SMS), multimedia message (MMS) or GPRS location identification.

However, there are non networked applications, that simply use the device platform to run the game software. The games may be installed over the air, they may be side loaded onto the handset with a cable, or they may be embedded on the handheld devices by the OEM or by the mobile operator.

Mobile games are usually downloaded via the mobile operator's radio network, but in some cases are also loaded into the mobile handsets when purchased, or via infrared connection, Bluetooth or memory card.
With the creation of the cell phone, one was easily impressed with the mere fact that the phone required no cables, but towards the end of the 20th century, cellular phones started to modernize, and people wanted more out of their cell phones.

With the introduction of the "candy bar" style cell phone, the appearance of a cell phone as well as its features and calling capabilities became a lot more important to people. Cell phone games were among the many new features that could be expected in this new type of cell phone.

Older cell phone games were not as expansive or as popular as console games, as the phone's hardware was not suited to high-color screens or sounds beyond differently pitched beeps. The games were usually animated with black squares. Some of the most common cell phone games were "snake" and "brick". Unlike today's modern cell phone games, which usually have to be purchased, these games came pre-installed on the cell phone, and could not be copied off or removed.

When the "camera phone" was introduced to the public, cell phones started to become a lot more common and a very big trend. The storage and graphic capabilities on these new phones were a lot better than the older "candy bar" style phone, which meant that higher quality games could be created for use on cellular phones. This of course also meant that companies could make a profit off these games.

Cell phone games are not as big of a success as they were thought to be because using a cell phone keypad as a controller is much different than any video game console. Also, the games available for cell phones are usually relatively short.

Today, cell phone games have come a very long way. Their graphics are about the same as you would expect on a 4th or 5th generation game console (which may not seem like a very big improvement yet is considered one because the game is being played on a cell phone). Cell phone games now tend to take up a large amount of memory on cell phones, which is part of the reason why they still aren’t too popular. Still, certain games such as "Tetris" and "Solitaire" are somewhat popular cell phone games.

Mobile games tend to be small in scope and often rely on good gameplay over flashy graphics, due to the lack of processing power of the client devices. One major problem for developers and publishers of mobile games is describing a game in such detail that it gives the customer enough information to make a purchasing decision. Currently, Mobile Games are mainly sold through Network Carriers / Operators portals and this means there are only a few lines of text and perhaps a screenshot of the game to excite the customer. Two strategies are followed by developers and publishers to combat this lack of purchasing information, firstly there is a reliance on powerful brands and licences that impart a suggestion of quality to the game such as Tomb Raider or Colin McRae and secondly there is the use of well known and established play patterns (game play mechanics that are instantly recognisable) such as Tetris, Space Invaders or Poker. Both these strategies are used to decrease the perceived level of risk that the customer feels when choosing a game to download from the carrier’s deck.

Recent innovations in mobile games include Singleplayer, Multiplayer and 3D graphics. Virtual love games belong to both of singleplayer and multiplayer games. Multiplayer games are quickly finding an audience, as developers take advantage of the ability to play against other people, a natural extension of the mobile phone’s connectivity. With the recent internet gambling boom various companies are taking advantage of the mobile market to attract customers, Ongame the founders of PokerRoom developed in 2005 a working mobile version of its poker software available in both play money and real money. The player can play the game in a singleplayer or multiplayer mode for real or play money. As well, the MMORPG boom seems to hit the world of mobile games. According to their website CipSoft has developed the first MMORPG for mobile phones, called TibiaME.