Eagle Time Plays OpenTTD

What options do we have for generating land?

A new generator and the old generator. TerraGenesis is the new (and probably improved) one.
If you mean the actual climate, there's temperate, which has everything; sub-tropical (more like a desert), which has water you need to supply towns with and mining diamonds to give to banks, as well as creating trees for sawmills to create goods with; and sub-arctic, which has snow lines where the towns above need food supplied to them, and gold is what's given to banks. We don't talk about Toyland.