The *.reko file extension is related to the RekoNet a card computer game. The *.reko file stores cardset.
REKO file extension - RekoNet cardset file
What is reko file? How to open reko files?
File type specification:
The REKO file extension is associated with the RekoNet a card computer game based on Klondike AGA Solitair card game for Amiga and other platforms. The *.reko file stores cardset.
RekoNet seems to be obsolete product.