RpgMaker is really approachable for a 13yo.
There also Luanti, the new name of MineTest, which is closer to the Roblox experience (in the sense that there already a playable game there, and creating new stuff is closing to modding than to game making).
The Roblox experience also includes a huge existing player base who may come and play your game without having to install anything new on their machines. I'd say this social factor actually matters a lot for Roblox where many if not most games are multiplayer.
The only thing close is minecraft, which from what I heard already has similar restrictions on in game chat, plus other shady maneuvers from Microsoft.
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