Boulder Dash Forum

Spills:

youtu.be/qzQdgcryJIY

No Trap, 7 To Grab:

youtu.be/kSIsSQa6qXU

Launch Base:

youtu.be/HLocwKJMncM

Blacklight:

youtu.be/n_Uvlw5-rHw

Balderdash 157:

youtu.be/-G840ivsTjY

Classic Remakes 99:

youtu.be/4n-rByaRMq4

DSM Dash 254:

youtu.be/di1aTTIgcvQ

Catacombs:

youtu.be/gr5yT-9p-_U

No Sandwich:

youtu.be/7WXkmNiKA6I

Double Dash 1 Cave N:

youtu.be/fLW-MutQvZo

Double 4F Free Rider:

youtu.be/h61TdOyWhsM

Happy New Year!:

youtu.be/5rS5ibTIGEw

I'm quite sure that "Marc de Haar" is meant. Also known under nickname "OdO", but he is not No1. He contributed caves to the Xmas game and created a small series of fangames as well, named "The Lost Levels". See:
https://www.boulder-dash.nl/bdgb/view_author.php?a=odo

A Nest of 2+5n Fireflies:

youtu.be/2kNvHSpHLU8

Balderdash 155:

youtu.be/SljtmVCdl9k