It's easy to think we know what to expect from Total War: Warhammer 3. The series has been around for more than 20 years and this is the third title in the fantasy spinoff branch. Sure, there will be new armies and a new map, but how much can developer Creative Assembly really shake things up?

Well, while a recent preview event didn't show off the full game, the new battle type I played was a welcome twist on the tried and tested formula. The new survival battles will come at key points in each faction's campaign and these crafted encounters are a real test of your moment to moment play.

I was taking control of the armies of Kislev, a human race banished to the cold northern plains of Warhammer's world. As well as wielding powerful frost magic, their armies have excellent cavalry and archers. They're also the fleshy wall that stands between the armies of Chaos and the civilizations that live to the south. So, as Khorne and his daemonic armies grow, it's Kislev that needs to trim them back.

I don't know of the context of the battle but my objective is clear. I've arrived at the gates of Khorne's citadel and I must push my Kislev army up the narrow corridor to the gates of his stronghold. I need to capture victory points along the way and withstand the waves of daemons that spawn to repel me.

The pressure in survival battles rarely lets up. As soon as the mission opens a small chaos army is already charging at my lines. Without the ability to pause the action or slow down the clock, I have to immediately arrange my troops to absorb the attack. Melee infantry form a line in front of my archers and I send my cavalry off to the flanks to wait until the enemy is exposed to an assault from the rear.

This first skirmish is easily won but it's also one of the few times in the battle I face a straightforward frontal charge.

The map is a long narrow corridor, a change from the traditionally wide battlefields in Total War games. It's also gated at key points, both with literal gates and magical barriers. So, at first, only a third of the map is open to me. I can only gain access to the next stage of the map by capturing a victory point. Easy enough, having already wiped out the meager forces defending it. However, as soon as I take the point it spawns in new waves of enemy troops on both sides of the battlefield.

I rearrange my army around the point to withstand the assault, but I also make use of a resource particular to survival battles: supply. It's an in-battle cash system that lets you buy reinforcements, heal and resupply troops, purchase upgrades for your soldiers, or even build fortifications. You get supply for every enemy you kill, but you also get a big bucket of the stuff when you capture a victory point.

I build a couple of towers which immediately start firing at the incoming daemons, whittling down their numbers, and I buy a few barricades to slow the enemy's approach. Most of the supply points go on bolstering my tiny army. I splurge on more melee troops and archers and they arrive at the victory point through a newly opened magical portal. I put them straight onto the barricades to repel the waves of daemons. At first I can only recruit basic troops, but with each victory point I capture I'll unlock the ability to recruit more advanced troops - like, and I cannot stress this enough, a giant magical bear.

After seeing off the waves of daemons, the first forcefield splitting the battlefield comes down and I can advance on the second victory point. There's another daemon army coming at me, though, and now until the battle is over daemons spawn in behind me. Not in huge numbers but enough to harass my army and threaten to take back the victory point I'd already captured.

This is how the pressure of the survival battle builds: even though I'm able to grow my army with the supplies I earn, from the start of the battle until I win, I'm facing larger and tougher waves of enemies, and a constant trickle of daemons nipping at the sides of my advance.

I smash through the regiment that's charging at me and take the second victory point. Again, waves of daemons spawn in at the sides of the map and I have to immediately put up fortifications and form my army into a defense. Except, now, as well as defending this newly captured victory point, the first is vulnerable, too. It's not game over if I lose control of one of the points, but any structures I've built will be demolished and, while the enemy holds them, my entire army suffers a debuff. So it's definitely to my advantage to keep control.

I see off the attack and call in more advanced troops, including a unit of bear-riding cavalry. In truth, I don't use them as well as I might - the action is all becoming quite messy so I don't have time to both manage the defense and line up cavalry for flanking charges - but I feel more secure simply knowing they're on the battlefield. I mean, the freaking bears.

With the waves defeated, the second forcefield falls, opening the way to the third and final victory point. Again, I face an army of daemons defending the objective, but there's even more ground to hold from the constant influx of enemy units.

I'm just about keeping it together: my forces are tired and depleted, and my ranged units have burned through most of their ammunition. I spend supply to restock my archers' quivers, I order a retreat on the units that have been thinned out the most and then re-recruit them to the field through the victory point portals. I need to be in as strong a position as I can when I take the third victory point because the final wave features Khorne's champion, an exalted greater daemon. A muscle-bound, winged, red daemon that wields a giant flaming whip. Thank goodness I've the supplies to summon in a magical polar bear.

When I take the final objective point and the daemon hordes come charging in I retreat to the second victory point where some of my fortifications still stand. I try to arrange my troops one last time but Khorne's forces smash through the line and I'm forced to pull back to the first victory point. I leave some melee troops to slow down the daemon's army and rapidly buy as many units as I can, spawning them in at the first portal I opened. This delaying tactic gives me the time I need to form a proper line and halt the daemon's advance and eventually overwhelm its army.

The greater daemon is the last soldier to fall and it makes a satisfying thump as the victory screen appears.

This will be the 15th Total War game Creative Assembly has made, but the short demo I played shows that the team is still finding ways to refresh the series. Survival battles are only a small piece of the game, and I've not yet seen anything of the campaign map or the other factions. But Total War: Warhammer 3 looks set to be an epic conclusion to the fantasy trilogy.