I got to try Lost Valley last night. This is a few years old, but was never distributed in the US (I suppose the on line stores may have it), so it didn't get a wide audience. I'd never seen it until recently, which is mildly surprising. Anyway, you and the other players are panning for gold.
The board starts off with just a big starting piece. Your pawns move along the 'edges' (except for the trading post on the starting piece), and whenever you come to unexplored area you flip up some rhomboids (?) to build the world. If you create a triangle-gap, there are triangle tiles as well ... these are 'better.' (This image explains it better than I can).
You can carry some resources (6 spaces worth). You start with tools, food and lumber, which you spend to do certain actions. On your turn you get to move 1 space (two if you follow the river) and an action, in either order. The most basic action is panning for gold, which costs food. Mining for gold (in the mountains) also costs lumber, but you have to build the mine.
The tricky thing is that in may spots, you have to spend an action (and equipment) to prepare. For example, to get gold out of the mountains you have to make a mine. To get gold out of the plains, you need to divert a stream. But once the mine is made (stream diverted, etc) then anyone can use it. So if you build a mine, any prospector nearby will run up and grab some gold.
The resource management works reasonably well. You need food to pan for gold (presumably you are out there for a long time), lumber to get gold out of mines, tools are useful for building fish traps (to get food faster), sawmills (to get lumber faster) and necessary to start a mine. You can buy plenty of great things in the trading post, which makes nice chrome. Since you basically get a single move and action, turns can fly by (once the world is explored a bit). In fact, I don't think our game lasted 70 minutes, like the geek claimed.
The fact that you don't own mines (etc) is interesting, in that it makes all the players reclusive and paranoid. The game ends when someone gets enough gold chits (each chit worth 1-2 from a river, or 3-4 from a mountain) or when you've explored enough of the world then via a timer. (Each turn having 1/3rd of a chance to advance the timer, which takes roughly a dozen advances to end).
We ended via the timer, and this felt unsatisfying. As the timer ticked down, the game dynamics shift. The earlier game dealt with jumping claims and running away from others. Later on the pressure means you don't have time to isolate yourself. This creates tension (get too far away from anyone, and you can't collude in the end game, get too close and you'll wind up losing some of the gold you worked for). I was glad to see the game end promptly, but it felt contrary to the earlier spirit.
I'd certainly try it again, though, but I'm not desperate.