There are three classic nokia phone games you can play on the nokia 5110 phone you get in the game. To get the games you have to find cartridges that are scattered around the game.
Game - Location
Bricks - The very right of the beach
Snake - Somewhere in the frontyard of uncle hayseed's house
Tennis - Somewhere in the burning spoke biker bar
The Cheat Ninja
On every Monday from 11pm to 12pm in southwest of the Imperial Estates, and Friday from 3am to 4am in northeast of the park's maze you can encounter the Cheat Ninja, who will sell you cheats. You'll notice that the game tells you what number day it is, and that you start the game on a Monday. That's day one. Then just add seven to find the next Monday.
To put it simply, Mondays are days: 1, 8, 15, 22, 29, 36, 43, 50, 57, 64, 71, 78, 85, 92, 99, 106, 113, 120, 127, 134, 141, 148, 155.