Rusty's Retirement has several farm types that you can unlock, such as River and Swamp. However, the game doesn't tell you how to unlock them.
Desktop Companion with IDLE FARMING – RUSTY'S RETIREMENT [Idle Farming Game]
When you first start the game, all of these different types of farms are locked, with no indication of how to unlock them. This leaves you with just the basic farm to start with while you find your way around and try to understand what exactly is going on.
If you still want to get the other biomes, there is an easy way to unlock them, but you have to be prepared to grind for hours.
To unlock additional farm types like River and Swamp in Rusty's Retirement, you must first clear all areas in the original farm by purchasing bulldozers.