It sounds like this party lacks URGENCY.
My solution would be - make them HUSTLE. Seriously, get campaign-events moving at a frenetic pace where the characters aren't always able to take a five-minute rest between encounters because giving away five minutes has an obvious cost to the party. Each individual "encounter" may not challenge the party, and doesn't have to be a long slug-fest .. but you start to get attrition-of-hit-points and attrition-of-encounter-powers (balanced by a funnel of action points in, and the fact that each individual encounter isn't quite able to challenge the party).
Here's some ideas:
- The survivors run away and alert the next room
. This encounter is always trouble, in any situation, especially if "the next room" attacks as the party are trying to take their five minute rest. (Warning: do not do this to 1st-level characters, its a TPK recipe).
- The Big Bad has captured the McGuffin and is getting away, leaving his henchmen in the way to delay you.
. This one works wonders - especially if you make it really clear that the Big Bad is getting away any time they try to rest.
- An epic battlefield with hundreds of creatures on both sides!
.. Focus on the party, throwing encounters at them with only a round or two to run some healing effects. Describe anything out of the scope of the "encounter" in general terms .. Can be especially effective if shown as, as the good guys win an encounter, something good happens elsewhere on the battlefield, but if they try to sit down and rest, the battle goes badly and teeters on the edge of disaster. (Works best if you build up to it over several sessions, for maximum epic-ness)
- Something too big to fight is chasing you!
.. The party realizes that their only hope is to press on through the enemies in front and try to find a safe refuge .. waiting too long will deliver them into the clutches of the pursuing army, rust monster, dragon, or whatever.
- The bad-environmental-effect is coming!
.. Flash flood, lava flow, collapsing tunnels .. you've seen it in hundreds of movies, usually right after James Bond pushes the convenient self-destruct button .. but there are always plenty of bad guys who are willing to fight even with the whole place coming down around their ears.
- Time is running out!
.. The evil ritual is just minutes from completion, the gate is opening, the bomb is set to go off at midnight and its 11:53 ..
You get the picture. There's no time to rest - and there might not even be time to sit here pounding on these bad guys! Better to break through and keep moving!!
...
You can get similar effects on a per-encounter basis with similar tricks:
- Artillery up on a cliff / ledge / wall / etc, overlooking a "killing field". A couple of Soldiers or Brutes block the way forward; the only obvious way up to the cliff / ledge / wall is a staircase on the opposite side of the Soldiers. Take the time to slug it out with the Soldiers, and the Artillery will pick you apart.
- After passing any form of T intersection, the party get attacked from both front and back; feels very scary because they are surrounded. Alternately, put a trap or environmental effect at their backs; a spreading fire with the bad guys between the party and safety turned a decent encounter into a movie-scene epic.
- The party encounters the BBEG and some henchmen mid-session .. as the party gets the upper hand, the BBEG turns and runs. If the party deals with the henchmen, the BBEG escapes. If the party pursues, he throws some more henchmen to delay them .. (second encounter with no rest) .. he runs again .. and oh the surviving henchmen from the first encounter are at your backs. (For added awesomeness, don't just chase him on foot, give yourself some kind of epic movie-esque chase scene through dangerous near-fatal terrain.)
Seriously, it takes a creativity .. but if you keep your sessions on a break-neck pace, your players won't have time to complain.
