For an individual project, I would develop an isometric pixel horror RPG based on the theme of escapism. Would definitely include gore.
Funds for the idea would be used to purchase commercial licenses for required assets, as well as any commercial plugins that may be needed.
If I had a budget of 5 million, I would start up a PC game development company. Singapore has a market for mobile game development, but not for console or PC.
I would hire a team to develop an indie game for Steam and PC.
For a paired project, I would develop a 3D puzzle game set in a space station. You play as an astronaut trapped in this space station.
The budget of $500 would be used to outsource the 3d modelling (if possible, as that is too little). If not, it will be used to purchase commercial licenses for necessary assets.