On several occasions, Nitrome has placed hints about upcoming games in already existing games. However, sometimes these hints are jokes. Nitrome hinting at an upcoming game is often an indicator that the upcoming game was made during or before the production of the game with the hint.
Below is a list of the times Nitrome has hinted an upcoming game, and this upcoming game was actually released.
Along with many unidentified enemies in the Classic skin, the house for Hot Air's Girlfriend appears on one hill with a character that is possibly Yin. A brain is seen selling some balloons from Hot Air 2.
The Snowman skin hints at Rubble Trouble New York and Tiny Castle. The demolition crew from the Rubble Trouble series appears (including Larry) trying to destroy a snow mound with the cannon, and the knight from Tiny Castle appears going into a small snow castle. It also hints at Ice Breaker: The Gathering 4 days before it was released with a giant snowman that looked like a Viking.
In the Ice Temple skin, Canary 214-LE appears firing into a rectangular prism that contains a Viking. Furthermore, the raccoon from The Bucket appears on top of his upside down bucket, and the mystical flying fish appears in the water. Brown and pink ice cream characters appear in the corner shooting ice and the white ice cream appears in a puddle. These are all references to Bad Ice Cream. The runners from Rush appear headed for a goal sign, as well as one who is squished by squish block from Enemy 585.
Several characters in Nitrome 2.0 are depicted before their release.
A Viking appears frozen in ice.
Below are a list of times Nitrome has hinted an upcoming game, but the game never was planned to exist, it is yet to come, or the game was cancelled without Nitrome ever informing fans that the upcoming game existed.