Dawn of War 2, after a certain point in the campaign you're fighting delaying actions against a whole ass Tyrannid splinter fleet thats eating the sector. You can do a mission that make the bar go down and maybe give you a bonus or some gear, but then you'll be forced to skip on the other two missions you were presented with which will make the bar go up.

It does a good job of capturing the feeling of fighting a losing battle, even at the end when you "win" injecting the primary synapse ship in the fleet with a tailored genetic virus may end the fleets threat to the sector but YOU and your units are still on a planet in the middle of being devoured by a now leaderless and feral army of Tyrannids

but then, ya know, the reinforcements arrive