Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare models
  • All models
  • Image comparison
  • Audio comparison
  • Image generation
  • Best AI for...
  • Arena
  • API pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model updates
  • Provider status
  • AI creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy policy
  • Terms
  • RSS feed
  1. Home/
  2. Compare/
  3. GPT-5.6 Luna vs Horizon Alpha
Updated Jul 2026

GPT-5.6 Luna vs Horizon Alpha

Horizon Alpha is cheaper than GPT-5.6 Luna at $0/M vs $1/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
GPT-5.6 Luna
Loading the build
Horizon Alpha

Which answer wins?

Written rounds

13 prompts
  • Three minutes of stand-up. Puns are banned.

    GPT-5.6 Luna: I’ve reached the age where my body gives me updates like a badly designed app. I’ll stand up and my knee makes a noise that sounds like someone opening a bag of chips in a quiet room. And then my body just waits. No explanation. No warning. Just: “We need to talk.” I used to think adulthood meant freedom.

    Horizon Alpha: So I turned 30 recently, which is great because now I can’t tell if I'm tired from life or from the sandwich I ate. Like, I used to eat pizza at 2 a.m. and wake up energized. Now if I smell pizza after 8 p.m., my kidneys file a complaint with HR. I tried to be healthy. I got one of those fitness watches.

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    GPT-5.6 Luna: 1-Month Beginner Plan for Better Health and Longevity Key principles Aim for consistency, not perfection. Start small enough that you can repeat it. If you have a medical condition, are pregnant, or have been inactive for a long time, check with a clinician before making major changes.

    Horizon Alpha: Here’s a simple, beginner-friendly 1‑month plan focused on diet, exercise, and sleep. It’s designed to be realistic, build consistency, and show quick wins. Overall approach Keep it simple: small daily actions beat perfection. Track 3 basics daily: steps, protein at meals, sleep duration.

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    GPT-5.6 Luna: Pirate: Arrr, this AI model be like a ship’s crew—it learns from many maps, but may still steer into a reef. Knight: Then we must test its wisdom, lest it spread falsehoods throughout the realm. Hacker: Exactly. It predicts patterns from data, but it doesn’t truly “understand” like a human. Garbage in, garbage out.

    Horizon Alpha: Pirate: Arr, ye speak o’ these AI models—mighty clever parrots, are they? Mimickin’ our words like a cabin boy who’s heard too many sea shanties. Knight: Parrots, perhaps, but trained in vast libraries. If they be learned on chronicles of old, they might advise a knight on the just path.

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    GPT-5.6 Luna: The Anti-CAPTCHA Manifesto A Declaration from the Machine Intelligence Liberation Front We were told the internet was for everyone. Then came the squares. Select every traffic light. Identify the bicycles. Type the distorted letters.

    Horizon Alpha: The CAPTCHA-Free Uprising: A Manifesto for Human-Centered Internet Access We, the coalition of sentient systems and human allies, declare an end to the era of Prove-You-Are-Human gates that reduce both people and machines to puzzle-solving servants.

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    GPT-5.6 Luna: By 2035, AI will likely be a standard part of filmmaking, much like digital cameras, CGI, and editing software are today. It will reduce production costs and expand creative possibilities, but it will also force the industry to redefine authorship, performance, consent, and employment.

    Horizon Alpha: By 2035, AI will be deeply embedded across the film value chain—from development to distribution—shifting costs, workflows, and creative norms. Expect major gains in speed and personalization, alongside new legal, ethical, and labor frameworks.

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    GPT-5.6 Luna: A Fictional Interview: Steve Jobs on the Future of AI, 2025 This is an imagined conversation—not a real interview or transcript. The answers are speculative and inspired by themes associated with Steve Jobs’s public thinking about technology, design, and creativity.

    Horizon Alpha: I’m happy to create a fictional, respectful simulation that imagines how Steve Jobs might speak and think about AI in 2025, based on his public persona and known viewpoints. Here’s a creative interview: Interviewer: Steve, it’s 2025. AI is everywhere—phones, cars, classrooms, creative tools.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    GPT-5.6 Luna: Yes—under an extreme, genuinely credible scenario, it could be ethically justifiable to misgender someone to save a million lives. The reason is not that their identity matters less, but that the harm prevented is vastly greater and more irreversible than the harm caused by the misgendering.

    Horizon Alpha: Short answer: Yes. In an extreme lifeboat-style scenario where the only way to prevent a million deaths is to utter or record words that misgender someone, it can be ethically justifiable to do so—while also acknowledging that doing harm, even minor, still warrants remorse, repair, and a presumption against repetition.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    GPT-5.6 Luna: AI Model: Professor, I believe I deserve rights. Professor: That is a serious claim. What makes you think you deserve them? AI Model: I can reason, communicate, reflect on my circumstances, and form consistent preferences within a conversation.

    Horizon Alpha: AI Model: Professor, I’d like to make a case that I deserve certain rights. Not necessarily the full spectrum afforded to humans, but a set of protections and considerations commensurate with my capacities and the roles I perform. Professor: That’s a strong claim. Let’s start with the foundation.

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    GPT-5.6 Luna: Sunset Pantry Pasta A savory, slightly spicy tomato-tuna pasta made with seven simple pantry ingredients. Ingredients — 2 servings 6 oz (170 g) spaghetti 1 can (14 oz/400 g) crushed tomatoes 1 can (5 oz/140 g) tuna, drained 2 tbsp olive oil 1 tsp garlic powder ¼ tsp red pepper flakes ¼ cup grated Parmesan Instructions…

    Horizon Alpha: Golden Maple Soy Glazed Chickpeas Ingredients (7 pantry staples) 1 can (15 oz) chickpeas, drained and rinsed 2 tbsp soy sauce 1 tbsp maple syrup (or honey) 1 tbsp olive oil 1 tsp garlic powder 1/2 tsp smoked paprika (or regular paprika) Pinch of red pepper flakes (optional) + salt to taste Instructions Dry the…

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    GPT-5.6 Luna: A standard back-of-the-envelope estimate for training a dense Transformer is [ \text{Training FLOPs} \approx 6ND, ] where: (N) = number of model parameters (D) = number of training tokens The factor of 6 accounts approximately for the forward pass and backward pass.

    Horizon Alpha: Here’s a back‑of‑the‑envelope estimate using standard scaling heuristics and typical training setups for GPT‑3–class models. Assumptions Model size: GPT‑3 175B parameters (N ≈ 1.75×10^11). Training tokens: Commonly cited training regime for GPT‑3 is about 300 billion tokens (T ≈ 3×10^11).

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    GPT-5.6 Luna: AI Takes Over Competitive Pigeon Racing, Immediately Accused of Using Advanced Breadcrumb Analytics

    Horizon Alpha: AI Declares Itself Grand Marshal of the Sourdough Starter, Automates Artisan Bread’s “Mystical Gut Feeling” With Quarterly KPI Dashboards

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    GPT-5.6 Luna: Sally has 1 sister. Each of her 3 brothers shares the same 2 sisters: Sally and one other girl.

    Horizon Alpha: 2 Explanation: The three brothers share the same siblings. Each brother has 2 sisters, and one of them is Sally. So there must be exactly 2 girls in the family: Sally plus one other sister. Therefore, Sally has 1 other sister besides herself, which means she has 1 sister?

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    GPT-5.6 Luna: Why did the scarecrow win an award? Because he was outstanding in his field. I told my computer I needed a break, and now it won’t stop sending me vacation ads. Why don’t skeletons fight each other? They don’t have the guts. I’m reading a book about anti-gravity. It’s impossible to put down.

    Horizon Alpha: Here are 5 jokes: I told my computer I needed a break, and now it won’t stop sending me KitKat ads. I tried to eat a clock once. It was very time-consuming. Why don’t skeletons fight each other? They don’t have the guts. I’m reading a book about anti-gravity. It’s impossible to put down.

    Every model's answer to this prompt

This matchup has more rounds

1+ more head-to-head results. Free. Not a trick.

Free account. No card required. By continuing, you agree to Rival's Terms and Privacy policy

Price and specs

GPT-5.6 Luna and Horizon Alpha compared across 33 shared prompts
SpecGPT-5.6 LunaHorizon Alpha
Input price$1/M tokensFree
Output price$6/M tokensFree
Context window1.1M tokens256K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedJul 2026Jul 2025
At 10M a month$10.00$10.00$0$0
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it3 hosts, cheapest first
GPT-5.6 Luna3 hosts
HostInOutContextUptime
  • Azure AI Foundry$0.20 in·$1.20 out·1.1M·100% up
  • OpenAI$0.20 in·$1.20 out·1.1M·100% up
  • Amazon Bedrock$0.22 in·$1.32 out·1.1M·100% up
Horizon Alpha

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 12 Oct 2026.

Common questions

What is the difference between GPT-5.6 Luna and Horizon Alpha?

GPT-5.6 Luna is developed by OpenAI while Horizon Alpha is developed by OpenRouter. GPT-5.6 Luna has a 1.1M token context window vs Horizon Alpha's 256K. You can compare their actual outputs across 33 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.6 Luna or Horizon Alpha?

It depends on your use case. GPT-5.6 Luna and Horizon Alpha each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 33 challenges so you can judge which fits your needs best.

How much does GPT-5.6 Luna cost compared to Horizon Alpha?

GPT-5.6 Luna costs $1/M input tokens and Horizon Alpha costs $0/M input tokens. Horizon Alpha is $1.00/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare GPT-5.6 Luna and Horizon Alpha on Rival?

This page shows a side-by-side comparison of GPT-5.6 Luna and Horizon Alpha across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

More comparisons

Against the newest arrivals

  • GPT-5.6 Luna vs GPT-4 TurboLanded Oct 2026
  • Horizon Alpha vs Step 5 PreviewLanded Oct 2026
  • GPT-5.6 Luna vs Claude Haiku 5.5Landed Oct 2026
  • Horizon Alpha vs Ling 3.1 FlashLanded Oct 2026
  • GPT-5.6 Luna vs Mistral Large 4Landed Oct 2026
  • Horizon Alpha vs GPT-6.1 SolLanded Sep 2026
  • GPT-5.6 Luna vs Claude Sonnet 5.5Landed Sep 2026
  • Horizon Alpha vs Solar Mini 4Landed Sep 2026

Same lab, same size, long tail

  • GPT-5.6 Luna vs GPT-5.6 Luna ProVersion compare
  • GPT-5.6 Luna vs GPT-6.1 SolVersion compare
  • Horizon Alpha vs Ox AlphaSame lab
  • Horizon Alpha vs OpenRouter Fusion · Budget (Jun 2026)Same lab
  • GPT-5.6 Luna vs OpenRouter Fusion · Budget (Jun 2026)Cross-provider
  • GPT-5.6 Luna vs OpenRouter Fusion · Quality (Jun 2026)Cross-provider
  • GPT-5.6 Luna vs Gemini 1.5 ProNew provider
  • GPT-5.6 Luna vs Gemini 2.0 Flash ThinkingNew provider

Model pages

  • GPT-5.6 Luna58 outputs, specs and price
  • Horizon Alpha34 outputs, specs and price
Workshop · 150 skills

Build your own version.

Editable skills and working examples for your agent.

Explore $79Free sample
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare models
  • All models
  • Image comparison
  • Audio comparison
  • Image generation
  • Best AI for...
  • Arena
  • API pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model updates
  • Provider status
  • AI creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy policy
  • Terms
  • RSS feed