A spatial deckbuilder where the ebbing tide shoves your whole board one cell every turn.
Spend energy to deploy units in your home half and cast spells on occupied cells, then end your turn to run the tide and combat. Each turn the tide slides every piece one cell, and it flips direction every three turns, so you must play to where the board will be, not where it is. Stop the invaders from reaching your home edge and clear every wave to win.
A deck-building game — the form popularised by Dominion, where the deck you draw from is itself the thing you construct — played on a board rather than in the abstract.
The original element is the tide. Every turn it shoves every piece one cell, and it reverses direction periodically, so the board is never where you left it and a unit placed for this turn is somewhere else by the next.
That forces deckbuilding and positioning to be solved together. Most games in the genre are about what your deck does; here a card's value depends on where the tide will have carried the board by the time you draw it, which makes timing a property of the deck rather than of the turn.
Deck of Tides fuses lane-defense card battling with a constantly shifting grid, turning board position into a moving target. It is an original, free browser deckbuilder on PlayPendium with daily and endless runs.