Tidal was initially built to become the example map for a tutorial on assaultpathing for UT2004. The entire layout, excluding minor tweaks, was built and playable within 3 hours. However, at the time I had little time and so the layout lingered on my harddrive for over a month before I touched it again. At that time UCMP3 kicked off and with practically no CTF map for that project, I decided to opt Tidal as an entry for UCMP3. It got accepted and later it was released in the third instalment of UCMP.
The map is small and tight. Really tight. It would be good for 2on2 or 3on3 CTF matches but not more since it would become rather spammy. It offers really smooth flow and the games are usually very fast since the layout connects well and there's only little distance to be covered to cap a flag.
Intended primarily for gameplay, the looks were much more of an afterthought than something planned.