Croquet was a 3D world written in Smalltalk. There's a promo video here: https://www.youtube.com/watch?v=mOZPW8l85eI
It's very exploratory, but the demos of a spreadsheet(!) with the 3D graphing and a live video avatar are really cute.
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Newspeak (an exploratory Smalltalk-style language) demo exploring combining method editing with debugging: https://www.youtube.com/watch?v=74WqdS_58uY