Seahaven Towers is FreeCell's board with two of its advantages taken away. You get the same four towers along the top, but two of them are already occupied before you make a move, and the tableau builds down in suit rather than in alternating colour. Every card is face up from the first second, so nothing is hidden — the whole difficulty is arithmetic you can see and still cannot escape.
It was designed by Art Cabral and spread through the early Macintosh solitaire collections, where its reputation was made: a game that looks like FreeCell, opens like a puzzle, and punishes FreeCell habits immediately.
You can never really move more than one card at a time. A five-card run travels by parking four cards somewhere and fetching them back, so the number you may move is exactly the room you have:
(1 + free towers) × 2empty columns
With two towers free and no spaces, that is three cards. Empty a column and it doubles to six. This is why an empty column is worth so much more than an empty tower — and why, in a game where only a king may fill one, emptying a column you cannot refill is often a mistake rather than a triumph.
One detail catches people out: when you move a run into an empty column, that column cannot also be used as working space for the move landing on it. Moving onto a card is worth twice as much as moving into a space.
The cards dealt into the towers are the opening problem. Two low cards are a gift; two kings are close to a lost deal, because a king in a tower cannot be built on and can only leave for an empty column you have not got yet. Look at them before anything else and decide whether the deal is worth playing.
In FreeCell a seven has two possible hosts of the opposite colour. Here it has exactly one card in the whole deck it can sit on, and one card that can sit on it. Long descending runs of a single suit are therefore rare and precious: never break one up to gain a single move, because you will not reassemble it.
Since only a king fills a space, a space is worthless unless you hold an accessible king. The correct order is almost always the reverse of instinct: find the king first, then dig out the column you intend to empty. Emptying a column with all four kings buried gains you a doubled move limit and nothing else, and you will usually have to fill it with the wrong thing to make progress.
Send aces and twos up as soon as you see them — they can never help you in the tableau. Higher cards are different. A six on the foundation is a six you cannot use to host a five, and in a suit-building game that host may be the only one available. Hold mid-ranking cards back until the matching lower cards are safe.
Before any long move, count the formula. Players lose Seahaven deals not by choosing the wrong card but by planning a six-card transfer with room for three, discovering it halfway through, and having to strand the remainder in towers they needed.
Every card is visible, so there is no luck left to blame — which means a lost position was a decision. Use undo to explore a line and come back. The game rewards reading three or four moves ahead more than any other member of the FreeCell family.