Need some inspiration? The Raspberry Pi Foundation have a great project finder resource: https://projects.raspberrypi.org/en/projects
From here you can select the type of software/language you’d like to work on, or find a project for hardware (Raspberry Pi, micro:bit and more) or by the topic that you’re interested in!
If you’re interested in getting into Unity, there’s also a great Introduction tutorial here: https://projects.raspberrypi.org/en/pathways/unity-intro
Not sure if Unity is for you, or how to get started? It could be worth having a read of the Unity Guide: https://projects.raspberrypi.org/en/projects/unity-guide