Shenmue I & II - the adventure/fighting titles wherein you peruse seedy locales in East Asia searching for Lan Di, the man who murdered your father, and develop interpesonal connections in order to do so, are both watersheds of artistry in the video game industry, as well as consistently aesthetically gorgeous (the first half of Shenmue II is unparalled, in my view). Of course, the series generated some backlash in spite of generally positive reviews - certain critics lamented it was too slow-paced, for example - but in a peculiar way, that was also the point, since as much as Metal Gear Solid or, in its own medium, Apocalypse Now!, Shenmue is challenging to the player to the point of suggesting post-modern impressionism: when the game infers you should "go make money", for example, to progress, the arduousness of the task almost seems deliberate; as if the game designers realized the whole experience would be more memorable if the player, like the protagonist, had to suffer through day-to-day pittances in order just to survive. Couple that recommendation with a notice of the game's lead designer - Yu Suzuki, the man behind OutRun, Virtua Fighter, and Space Harrier, among others - and you'd be hard-pressed to find more essential releases in the Dreamcast catalogue.
Also:
- Soul Calibur - saved the fighting genre from the perverse, post-Street Fighter influx of increasingly complex, combo-based fighters; reprioritizing the significance of timing and zoning in the process.
- Jet Grind Radio - not as great as its sequel, Jet Set Radio Future for Xbox, but still a quirky, excellent, 3D something-or-other for the DC, and - whatever else - superior to Sonic Adventure.
- Spider-Man - a PSX classic, and worth playing on the Dreamcast if you haven't: via strengthened hardware, the game uses non-linearity to its advantage, ensuring a closer reenactment of the spidey experience than seen on consoles before (plus, webs that attach to nowhere).
- Power Stone 1 & 2 - whether the first or second is better is a fractious debate, though I'll opt for the first, and comment also that this is the best, hectic "accesible"-type 3D fighting franchise (a common genre, as you can imagine) to have been birthed since Super Smash Bros.
- Virtua Tennis - really just glorified Pong, but that's alright, since with a few refinements, "Pong" turns out to be the best offering this side of FantaVison, not to mention a great tennis sim.
- Marvel vs. Capcom 2 - zany, of course, as well as so over-the-top in terms of the ease of combo execution that a brief mash of the buttons has the equivalent of two atomic bombs and the July 4th fireworks, but it's nonetheless cool to assemble Spider-Man, Chun Li, and Wolverine on the same tag team, as well as just to encounter nonsense this infinitely playable.