What storyline in King's Field? :P As far as I can tell, it's basically "Descent into the pits of hell and fight Satan", haha. I'd recommend it to King's Field fans too. Just watch out for the option in the game's menu that formats your entire memory card... I lost a 100 hour Tactics Ogre file I wasn't even done with yet that way. :/

There's also Shadow Tower Abyss on PS2, for that matter. Similar stuff, but definitely a lot fancier. The first King's Field actually came out in 1994 and was one of the very first PlayStation games, so it's also interesting for the historical aspect.

Getting back to PS1, there's plenty of great Konami shooters to look into. I'm partial to the Detana TwinBee Yahho! Deluxe Pack, but there's also Parodius and Gradius Gaiden. On the subject of TwinBee, there's also TwinBee Taisen Puzzle Dama, a fun Puyo Puyo-style puzzle game. Honestly, you could go with any Taisen Puzzle Dama on PS1, but the TwinBee version is the best value because it also include the full arcade original. Can't beat two games in one.

If you want something really silly, try out Bakusou Dekotora Densetsu: Art Truck Battle to play a Japanese truck driver, racing against other drivers to make your deliveries, and customizing every detail of your truck with lights, art, you name it.

If you don't mind checking a FAQ a tiny bit, I recommend Ganbare Goemon: Ooedo Daikaiten since the stages are straight-to-the-point 2D platforming. It's a little derivative for a Goemon game (mostly based on 2), but it's still good fun.

I could recommend a bunch of games that are more text-heavy, but I'll just leave it at that, at least for now.