Slightly less difficult than Ghosts n' Golbins but you're thinking of the good system (NES).

Handheld systems... my Achilles' heel... I don't have any more guesses.

Ninja Gaiden then!

Though that game's also ridiculously hard .

Super Mario Bros. Deluxe?

Yep Ninja Gaiden II.

Good guess, but this game and its handheld came later.

Another hint: the game I'm describing has a number in the title.

Not Dragon Quest, although one of the main antagonists is a dragon....or something like that.

As guessed by Smeags and TruckO'saurus (need more minerals!):

32. Starcraft + Brood War expansion (PC, also on N64 as Starcraft 64)

Talk about unoriginal! This game adding nothing new to RTS gameplay; 2 resources, 3 factions, basic RTS techs and units. It just did it all prefectly. Very few games in the genre are as amazingly polished as this one. The 3 races were incredibly well balanced and in the coming years were patched to perfection whilst they managed to incorporate a decent campaign mode into the game on top of the e-sport multiplayer.

#32 - LittleBigPlanet 2 (PS3)

As guessed by Miz.  An absolute treat of a platforming game and a fantastic way to follow up one of the most unique titles on the PS3.  While LBP2 lost something in the story mode (or perhaps LBP1 just had that special magic) but regardless, it more than made it up with it with fantastic creations tools and a skilled community, making to this day some of the most inventive levels I've seen.  All the colourful and vibrant 2D platformers are still here but they're mixed in with first person shooters, isometric racing games, top down RPG's and so much more.  Some of the many reasons I keep on returning to this game.

Clue for my #31 - Multi-plat follow up to a PS2-exclusive exclusive launch title featuring insane drops and tricky gameplay.

Clue for 31: A four-sided shape, a clock and a gun.