TIC-80
An open fantasy console with built-in code, sprite, map, SFX, and music editors plus fixed display, palette, and cartridge limits.
Why use it
Jams and early mechanic tests can stay in one tool, while explicit constraints force teams to identify the core loop quickly.
Where it fits
Use prototypes and playtests to find core experience problems while they are still cheap to fix.
What to check
Check current free-versus-Pro export features; fantasy-hardware limits do not model target-platform performance, and commercial work must also clear language and asset licenses.