Feasibility of changeable terrain

[Shinhan]

I want to make MMORPG (based on 2D game www.toadwater.com) that uses changeable terrain.
Players should be able to plant trees (and have those trees grow), build houses, chip rocks, and dig holes. Im not looking for realistic simulation of hole digging, but ability to make a hole with one click, and a ditch with few more is needed.
How hard is to do something like that?
And if not in CS, where would it be possible to implement?

Thanks for any help 

[KPNRG]

Probably the easiest would be a simple 2dimensional texture, which appears like a ditch, to be placed - a few things could be done to add illusion of depth, but in the context of a 3d engine, this approach is unlikely to be very satisfactory.

But I suspect you might rather be looking for deformable terrain...

[jorrit]

I want to make MMORPG (based on 2D game www.toadwater.com) that uses changeable terrain.
Players should be able to plant trees (and have those trees grow), build houses, chip rocks, and dig holes. Im not looking for realistic simulation of hole digging, but ability to make a hole with one click, and a ditch with few more is needed.
How hard is to do something like that?
And if not in CS, where would it be possible to implement?

Thanks for any help 

In theory the CS terrain engine can *almost* do it. It does require some modifications here and there so it does require someone with time and knowledge to actually do that.

Greetings,