Changing Tides is a very thorough, mechanically well constructed game, featuring a transformative adventure beneath the waves.  The system seems simple but effective at providing both challenges and the tools to handle them, through the use of an impressive amount of tables and charts, presenting a GM with a wide array of escalating biomes and specific hurdles for the players to interact with, all of which are set up for memorable and unique encounters, providing a robust framework for the GM to hit the ground running without a lot of time for "crunch".  These are all laid out in a simple format, easy to read and reference system.

I believe that the game could be significantly more interesting on a narrative level, and here is where it stumbles somewhat.  The game shines in its mechanical features, but at is bogged down by the same.  Much of the focus is taken up by determining what a specific die roll does, when it is made and how many static numbers to add to it, but there is little in regard for a larger narrative framework.  No information is provided to ground the setting or characters or provide an imaginative hook.  Even the artifact, the center of the story, is never really touched upon, merely remaining as a vague macguffin.  This absence of setting, character or plot does the well thought-out mechanics a disservice, making the affair read like a collection of dry charts and basic math.  A solid two pages are dedicated to meticulously stating out the mechanics of individual creatures, but it is never tied together with anything more compelling than rote application.  The changes, the core of the game, seem arbitrary, reduced to pure mechanical attributes.

Changing Tides clearly has some thought and effort behind it, providing a solid mechanical side.  The foray into narrative context that it does make, in the form of the individual hurdles, shows that with a little bit more of a focus, this game could really provide a solid experience along the lines of Subnautica, exploring the depths of a mysterious sea deeper and deeper.  I really like the competitive nature that seems present here, and think that race to the single prize as individuals, rather than a party, provides some very interesting opportunities.  In conclusion, Changing Tides seems like the reference table on a GM screen, crucial to a game, but lacking the spark to tie it together.  It is a good game, but with just a little push, it could be a great one.