So, I was wondering to myself if it were ever possible to come up with a situation where one side was FORCED to checkmate the other, with best play from both sides. 

The best I've been able to come up with so far is this, where white is FORCED to mate black in one move.

This leaves me wondering though- is it possible to come up with forced mating sequences, not just positions? 

That's where you come in. I know there are many cleverer chess players out there then myself, so consider this a challenge to come up with a forced mating sequence and post it here. (Or, if it helps motivate you, consider it a competition to see who can come up with the longest sequence.)

I look forward to seeing what you can come up with!

So, you're not talking about a regular selfmate?

No, not a regular selfmate. Those can be clever too, but this is a lot trickier I think.

simple pattern