How do you follow up on a four-hour pack-in title that blew up into a phenomenon that defined a year-plus of gaming culture? Game creator Valve decided to flesh out the concepts pioneered in “Portal,” coloring in some existing wireframes, adding details to older sketches, and doodling new expansions to previous ideas in the margins. Without turning the page, the team has painted a much richer picture that seizes your attention in a steel grip even if it’s telling a similar story.

Like the original, so much of what makes “Portal 2” special is in the execution and the originality of standing in heroine Chell’s shoes and experiencing her destiny. Any spoilers would seriously detract from the game. Not because the plot relies on contrived twists — the major beats are telegraphed in advance — but because Valve has leveraged the interactive experience perfectly. Weathering the taunts of a sadistic AI as you’re trying to survive its deadly challenges is unlike passively watching HAL-9000 try to kill off meddling astronauts. Gruesome depictions of abandoned experiments take on a new horror when you’re desperately avoiding a similar fate yourself. The dialogue’s pitch-perfect delivery is half of the genius of “Portal 2,” and it would be a shame to ruin the brilliant comedic timing or any of the other many nuances Valve so painstakingly crafted in this review.

This isn’t to say that “Portal 2” takes itself too seriously. On the contrary, the sequel goes in a dramatically opposite direction than the “Half-Life” tie-in that many predicted. Descriptions of violent, painful death are played for a laugh more often than not. The villain GLaDOS’ blithe disregard for human suffering is again a recurring comedic theme. The touch of gravitas here and there is just enough to ground the writing and serve as a contrast to the game’s goofy world. I would have preferred Valve to play it slightly straighter and give a look into what catastrophic events led to the current sorry state of Chell’s world, but that’s the sci-fi nerd in me talking. We don’t need to know why the Enrichment Center is; that it is trying to kill us is enough.

I was concerned that I would tire of “Portal’s” one-note shtick, however amusing, over the course of a full-length game. Adding two major speaking roles and a few different environments, along with carrying over the masterful pacing of the original, keeps the single-player adventure fresh through its entire eight-hour span. I never once thought I’d place GLaDOS second on any list of “Portal” characters, but J.K. Simmons’ character surpasses the malevolent AI even though she’s as amusing as ever. I was never bored of the dialogue, settings, or puzzles. The constant introduction of new elements ensured that I never even came close.

The co-op campaign, on the other hand, is five hours of relatively simplistic GLaDOS banter with occasional hijinks from the cooperative testing robots. Co-op play is more mechanics-driven, with occasional bits of hilarity injected by GLaDOS’ amusing attempts to sow enmity between the two of you. The puzzles are ingenious, and the simple ability to put a marker in the game world makes plotting strategies out smooth and easy. I wasn’t sure about co-op puzzle-solving beforehand, but “Portal 2” made me a rabid believer. Do whatever it takes to find someone to tackle these challenges with. They’re that good.

As for the puzzles themselves, they’re wonderful. “Portal 2” has fewer agility-driven obstacles, so less dextrous gamers shouldn’t find themselves stuck on anything for lack of stick-flicking ability. The new elements are each great in their own rights, and they work together beautifully.

The game’s quality stays consistently outstanding throughout; there isn’t a minute of filler content to be found anywhere in single-player or co-op. I would have loved to see something unique done with the story, which doesn’t end anywhere interesting despite a reasonably satisfying ending. That said, the next game I want to play is a second run through of “Portal 2,” because the existing formula is excellent and brilliantly executed.

‘Portal 2’

9.5 (out of 10)

PlayStation 3, Xbox 360, PC

Valve Software, Electronic Arts

ESRB rating: E10+

Weekly download

‘Section 8: Prejudice’

Reviewed for: Xbox 360 (via Xbox Live Arcade)

From: TimeGate Studios

ESRB Rating: Teen (blood, language, violence)

Price: $15

Were “Section 8: Prejudice” a full-priced first-person shooter, it’d be recommendable as a flawed but endearing breath of fresh air. At $15, though, it’s simply a no-brainer. From the visual presentation (good, but a couple years behind its big-budget counterparts) to the enemy A.I. (also good, but occasionally prone to significant lapses in judgment), “Prejudice’s” campaign doesn’t completely mask its smaller budget.

At the same time, though, its warzones are wider and higher than the constrictive corridors that dominate most shooters, and it gives you the necessary tools — jet packs, mechs, vehicles that are wildly fun to operate — to take advantage of all that space. “Prejudice’s” campaign is comparable in length to a $60 shooter, and its 32-player competitive multiplayer includes unlockable perks, bot support and even some light real-time strategy mechanics. Warts or not, everything about “Prejudice” operates with a great mix of competence and chaos, and the total package is a total steal at this price.

— Billy O’Keefe, McClatchy-Tribune News Service

New game releases

The following titles were scheduled for release the week of April 24:

• “Aladdin Magic Racer” (Wii)

• “Castlevania: Lords of Shadow – Resurrection” (X360, PS3)

• “Nin2-Jump” (X360)

• “Outland” (X360, PS3)

• “Trouble Witches Neo!” (X360)

• “ZEN Pinball: Sorcerer’s Lair” (PS3)

• “Man vs. Wild” (X360, Wii, PS3)

• “Remington Super Slam Hunting: Alaska” (Wii)

• “Airport Mania: First Flight” (DS)

• “Darkspore” (PC)

• “Hector: Badge of Carnage” (Mac, PC)

• “The Next Big Thing” (Mac, PC)

• “Jurassic Park: The Game” (Mac, PC)

— Gamespot.com

Top 10

DOWNLOADS

The editors of Game Informer Magazine rank the top 10 downloadable games for April:

1. “Outland” (PS3, X360)

2. “Torchlight” (X360)

3. “Mass Effect 2: Arrival” (PS3, X360)

4. “The Dishwasher: Vampire Smile” (X360)

5. “Hard Corps: Uprising” (PS3, X360)

6. “Beyond Good & Evil HD” (X360)

7. “Might & Magic: Clash of Heroes HD” (PS3, X360)

8. “Assassin’s Creed Brotherhood: The Da Vinci Disappearance” (PS3, X360)

9. “Chime Super Deluxe” (PS3)

10. “Swarm” (PS3, X360)

— McClatchy-Tribune News Service