OpenAI just cut the price of its cheapest GPT-5.6 model by 80 percent, three weeks after launch - the clearest signal yet that the company that kicked off the generative AI boom is being dragged into a price war it did not start. On Thursday the company said GPT-5.6 Luna, its speed-focused model, now costs 20 cents per million input tokens and $1.20 per million output tokens, down from $1 and $6. GPT-5.6 Terra, the mid-tier model, gets a 20 percent trim to $2 per million input tokens and $12 per million output. OpenAI's GPT-5.6 family consists of three tiers: Sol (highest capability), Terra (balanced), and Luna (fastest). Whether the cuts are enough to slow the shift toward cheaper alternatives remains to be seen.