This first portable Dynasty Warriors was a launch title, and it ended up just kind of being a hasty reworking of Dynasty Warriors 4, presumably just to get something out the door. So in some ways it's just a more limited portable version of that game, but it does have a couple of unique strategy twists not seen in the mainline games that make it a little more interesting. Also, if you're gonna copy assets, DW4 is the one to pick since it had the best butt rock of the series by far.
So you've still got the standard Shu / Wu / Wei campaigns to start out with, but the map selection is far more limited than in DW4. Each campaign has only six maps, the first two are shared between all of them, and each further shares at least two more with one other faction. Can't play as the big dogs like Cao Cao and Liu Bei initially either, have to unlock that by completing their campaign at least once.
The PSP would choke to death on the sprawling maps and hundreds of simultaneous characters of the PS2 games, so the solution here is to break the maps up into smaller self-contained squares. You move between adjacent squares, but will have to fight if you move to a square occupied by an enemy. While you're in battle, the enemy generals also make their own moves around the board, and can even pop into your square to reinforce their buds -- but your allied generals can jump in for support, too.
The basic goal is to go after the enemy's main camp. Technically, they can capture your camp too, but I never once saw them make a serious push to actually do that. Death comes from your playable character getting killed on the battlefield, or your army running out of supplies. "Supplies" is really just a code for how much time you have to work your way through each battle and capture the enemy camp. Along the way, you can tack on a few more minutes here and there by capturing enemy supply depots, but they can also steal time from you by taking over supply depots that you hold. You can also stop into your supply depots to heal your character and their officers, at the cost of some of your time.
This whole arrangement actually adds a little more of a strategic bent to the proceedings. You have to plan your route more carefully, since you rarely have much more than 20 or 30 minutes overall to get through the entire map. But the enemy generals are roundly pretty tough in this one, so you also have to power-up on some hapless patrol units en route to be able to go toe-to-toe with them. Having multiple enemy generals jump you in a square almost always gets you killed, so the best bet is usually to plan a clever and more roundabout path around them while still trying to pick up some supply depots en route. But it also helps to spring your ally generals from their conflicts so they can help you bum rush the fortifications where two or three tough enemy generals and their officers might be camping.
Morale is more important here than it is in the mainline games, too. You win squares by knocking the enemy morale down to zero, rather than killing their generals or entirely eliminating squads of troops. In fact, oftentimes you can totally avoid a powerful general and just plow reams of his mooks to reduce morale and force him to surrender! Fresh troops continue to spawn in for both sides until someone's morale hits zero and they are forced to surrender. If that's you, you don't die, but you do get kicked back to your starting camp.
You also earn officers after each battle, up to four of which can be taken into future battles. Each has their own stats and battle abilities, but may also pump up your main character's stats as well. Apparently they could be traded between players, but you'll not likely be doing that now. If an officer is with you during a failed campign, they're gone until you win them again in some future battle.
So the game is actually more strategic than the PS2 entries, yet maintains the same satisfying core beat-em-up gameplay. So what's the problem? Well, the main one is technical limitations. Draw distances are abhorrent, with whole enemy squads just suddenly appearing right in front of you all the time. You really have to lean on the radar, which you access by pressing the Select button -- but when the game has some notification about other stuff going on in the map, it takes that away from you for a few seconds! And if you grumbled at the camera limitations and constant backshooting by enemy generals and officers in the PS2 game, it ain't any better here with the pop-in characters and 1/3 of the screen taken up with other stuff.
Ultimately, you wish they'd done more -- more new assets, more maps, more playable characters -- but this first portable excursion at least nails the basic gameplay and feel capably with just some tolerable technical limitations. It's a damn sight better than that abortion for Nintendo DS, anyway. And I'd like to see the strategy elements here implemented into a mainline game somehow! Worth checking out for series fans, but might be too rough of an introduction for newcomers.