I can highly recommend TuringComplete. If you know what you're doing the start can feel a little hand-holdy, but by the end of the game you have a functioning c

I can highly recommend TuringComplete. If you know what you're doing the start can feel a little hand-holdy, but by the end of the game you have a functioning computer running an assembly language of your design and it's fairly close to an open sandbox. Building up to that point having started from the basics was very neat