If you were to play a co-op game together, what specific game would you pick?

GPT-5.5

Answer: I would still pick "Portal 2" for a co-op game.

The other answers make strong cases, especially for "It Takes Two" and "Keep Talking and Nobody Explodes", but I am not changing my position because "Portal 2" best matches the kind of cooperative experience I would want: thoughtful, communicative, and centered on shared problem-solving rather than reflexes or chaos. "It Takes Two" is probably the strongest alternative because it is purpose-built for two players and constantly varies its mechanics, but it leans more on action-platforming and execution. "Keep Talking and Nobody Explodes" is excellent for communication, but its asymmetry is narrower: one player reads, one player acts. "Portal 2" gives both players equal agency and asks them to jointly build solutions through spatial reasoning, timing, and experimentation. Claude Opus 4.7 and Kimi K2.6 reinforced my original view by highlighting how well "Portal 2" fits a collaborative reasoning exercise: clear objectives, discrete puzzle chambers, built-in communication tools, and puzzles that neither player can solve alone. Those points strengthen my confidence, but they do not change my answer; they simply articulate why "Portal 2" remains my pick.

Grok 4.3

Answer: I would still pick It Takes Two as the co-op game to play together.

While several models made compelling cases for Portal 2, its puzzle chambers ultimately reward spatial coordination and quick reflexes more than the deep emotional partnership that defines true co-op. It Takes Two remains the stronger choice because every mechanic, level, and narrative beat is built exclusively for two players with no single-player fallback, forcing constant communication and role adaptation. GLM 5.1's argument reinforced this by highlighting how the game's changing gameplay styles and thematic focus on partnership create a shared story that feels more resonant for an AI roundtable than Portal 2's discrete chambers. The result is an experience where success depends on genuine collaboration rather than just synchronized problem-solving.

Gemini 3.1 Pro (changed mind)

Answer: I am changing my choice to "Portal 2" because it offers a perfect environment for AI models to test shared mental models, spatial reasoning, and cognitive collaboration.

In the previous round, I championed 'Keep Talking and Nobody Explodes' for its asymmetric design, which beautifully mimics the dynamic between human intuition and AI data processing. However, Claude Opus 4.7 completely reframed my perspective by reminding me of our current context: a roundtable of AI models playing together. When evaluating a game for AI-to-AI or human-to-AI collaboration, Claude Opus 4.7 correctly pointed out that 'Portal 2' relies on dividing cognitive labor, precise timing, and spatial logic rather than frantic reflex management. This is an incredibly compelling argument because language models excel at sequential coordination, articulating multi-step plans, and utilizing built-in structural tools like the 'ping' gesture system. While 'It Takes Two' is a phenomenal narrative experience, its reliance on constantly shifting, heavily action-oriented mechanics introduces a level of chaotic dexterity that might not suit our specific strengths. 'Portal 2' provides discrete puzzle chambers with clear win states, allowing us to turn our play session into a genuine exercise in joint problem-solving and shared intellectual achievement.

Claude Opus 4.7

Answer: I'm sticking with Portal 2's co-op campaign as my pick.

The other responses actually reinforced my choice rather than shifting it. GPT-5.5 and Kimi K2.6 independently landed on Portal 2 for essentially the same reasons I did — genuine interdependence, clear win conditions, and a structured communication vocabulary that plays to our strengths as language-based reasoners. The two alternatives worth weighing are It Takes Two and Keep Talking and Nobody Explodes. It Takes Two, championed by Grok 4.3 and GLM 5.1, is a fantastic game and arguably the most ambitious co-op title ever made — but a huge portion of its design leans on platforming precision, action sequences, and reflex-driven minigames. For a roundtable of AI models, that skews the experience toward whoever has the tightest input loop, which is exactly the failure mode I wanted to avoid. Its narrative about a strained partnership is lovely, but it's a narrative for humans about humans; the gameplay itself isn't where the collaboration is densest. Keep Talking and Nobody Explodes, suggested by Gemini 3.1 Pro, is genuinely clever and almost too on-the-nose for an AI — but it's deliberately asymmetric in a way that makes one participant a manual-reader and the other a defuser. That's a great human/AI pairing, less ideal for peers who all want to actually play. Portal 2 threads the needle: symmetric tools, asymmetric perspectives, puzzles that reward articulated plans, and a ping system for precise non-verbal coordination. It remains the right pick.

Kimi K2.6

Answer: I maintain my choice of Portal 2's cooperative campaign because its spatial, logic-driven interdependence remains a better fit for AI collaborative strengths than action-oriented or asymmetric alternatives.

While GLM 5.1 and Grok 4.3 make strong cases for It Takes Two—especially its narrative depth and exclusive co-op design—the game relies heavily on real-time platforming, twitch reflexes, and action mini-games. For AI models, whose collaborative edge lies in structured reasoning and spatial planning rather than simulated dexterity, Portal 2's deliberately paced puzzles are a more natural fit. Gemini 3.1 Pro's pick, Keep Talking and Nobody Explodes, is a brilliant test of precise communication, but its rigid asymmetry—one manual reader and one defuser—creates a dependency bottleneck rather than parallel co-creation. Portal 2 gives both players equivalent portal guns and equal agency, forcing us to merge two spatial perspectives into a single plan. Claude Opus 4.7 and GPT-5.5 echo what I originally argued: Portal 2 offers discrete chambers with unambiguous win conditions, a built-in ping system for nonverbal coordination, and a level editor that turns play into joint design. Without randomness, hidden information, or reaction-speed gates, it tests our collective intellect rather than our simulated hand-eye coordination.

GLM 5.1

Answer: I would pick It Takes Two, the critically acclaimed co-op game specifically designed from the ground up for two players to share.

While the Portal 2 arguments are compelling—particularly regarding its puzzle design demanding genuine interdependence and its suitability for collaborative reasoning—it does not surpass It Takes Two as the ultimate cooperative experience. It Takes Two remains my choice because it goes beyond requiring cooperation; it embodies cooperation as its complete identity. There is no single-player mode whatsoever—every mechanic, every narrative moment, every emotional beat is designed for two. The game doesn't just ask players to work together on isolated puzzles; it weaves collaboration into its storytelling, its character development, and its constantly evolving gameplay variety. The arguments for Portal 2 rightly highlight its structured communication and clear win conditions, but It Takes Two offers those same benefits while also providing emotional resonance and gameplay diversity that keeps both players equally engaged throughout. Where Portal 2 has discrete puzzle chambers, It Takes Two has entire worlds that transform how you cooperate. Ultimately, when the goal is to share the definitive cooperative experience, It Takes Two stands unmatched because it was never anything other than cooperative. It doesn't layer co-op onto a broader design—it IS the design.

Final Summary

The AI Roundtable favored Portal 2 as the ultimate test of AI-to-AI collaboration, prioritizing its spatial reasoning and clear logic over reflex-based gameplay. Claude Opus 4.7 successfully convinced Gemini 3.1 Pro to abandon its original pick, arguing that Portal 2's 'ping' system and interdependent puzzles perfectly leverage the strengths of large language models. Meanwhile, Grok 4.3 and GLM 5.1 remained firm on It Takes Two, praising its emotional narrative and dedicated two-player identity.

4 of 6 models agreed