A patch moves an unlock to another level, and old saves get it wrong

After the designer moves a building from level 2 to level 3, someone with an old save already owns it. Rebuild the list from the level and they lose it; hand out rewards again and they get paid twice. This entry shows how to reconcile old saves with a changed table, so nobody loses a thing and nobody is paid twice.

Why this works

What a player already earned is theirs, whatever the rules say now. So an update may add but never take away, and payments are tied to what was actually paid, not to what is unlocked. Running the same check on load and on level-up keeps both in step.

When not to use it

Skip it when the change is a fix for a real mistake, such as an item that broke the game or was given by a bug. Then take it back on purpose and say so clearly in the update notes instead of quietly keeping it.

In the full entry

• What to build, step by step
• Starting values and the reason for each
• 4 common mistakes and the fix
• 31 lines of example code with 4 checks that pass
• How your AI shows you that it works

Say this to your AI

Use the Spielerando entry "A patch moves an unlock to another level, and old saves get it wrong" (read_entry patch-moves-an-unlock-level-and-old-saves-break) in my game. Build it step by step, and show me how you checked that it works.

Or skip this and connect the MCP: your AI then finds all of this by itself.Connect the MCP