Most solitaire games feel like a puzzle. The main reason is that you are trying to play a game against a system. To make sure you do not lose the game, you try to make the optimal decisions. Analyzing which solution is the best could feel like a puzzle as there is most of the time 1 optimal solution. There is no place for sub-optimal strategy as this could cost you the game.
I had an idea for another approach where the game has an objective to win the game, but there is no way to loose. Failing certain actions or your whole plan will only set you back for some time to make you stronger later. So eventually you are going to win the game, it's just a matter of how and when.
You could have a scoring mechanism to grade your success, or a achievement mechanism to try various path. Or how much time it tooks to get a specific score.
I did not see that many game that using this structure. One game that passes in my head is Nemo's War where you are not in a race against a system. But there are risks, and you could actually die and lose the game.
The concept I am proposing also have some similarities with Sandbox games.
The whole idea is to allow players to make sub-optimal choices for the fun of it. Which is impossible when you are racing against a system or against other players.
Do you think such game could work?
Do you know games that has a similar structure?
Maybe I could illustrate with an example: This is just one of the possible idea.
The game first starts as an adventure game where you wander around the kingdom fullfill quests, gaining power, gaining rank and influence. Eventually, you'll be powerful enought to try taking over the kingdom either by military force, by marrying an well positionned noble and assasinating the opposition, by destroying the kingdom and ruling on a land of ashes, etc. The game ends when you are king, no matter the path to victory.
There could be scenario that changes the behavior of the game, giving you new opportinities and new ways to take advantage of the situation. For example: An uprising, allowing you to chose sides defend the kingdom to gain rank, join the rebels to support the uprising so that they crown you king, or let the ennemy fight each other then attack when both sides are weak.
There will be not any way to lose. You could end up wounded permently, jailed, or exiled. Buy all those events are there as a temporary failure to make you stronger afterwards.
Aging could be a way to make sure the game ends eventually.