Mobile games are incredibly common. If you have a phone, chances are you have or had at least one mobile game installed on your phone.
What was the first mobile game?
For this question, a mobile game is any game that can be played on a small handheld device (including but not limited to modern smartphones). Games played on hand-held game consoles (such as the Gameboy or 3DS) count. If external controllers or being plugged into a display device are required, it is disqualified. The answer has to include both the game and the device it is played on.