Each player is a druid who starts with the same eight-card deck, with cards having a number (100-107 in this case), 1-3 spell points (in red, blue, green, yellow, or multicolor), and an effect. On a turn, you have four cards in hand and are going to do one of three things:
• Acquire creatures: To use your druidic powers to call creatures to your side, discard cards from your hand with the same color of spell points, then use those points to "purchase" creature cards from the board and add them to your discard pile, with creatures costing 1-4 points. (You can buy cards of any color, but all the cards you discard must be of the same color or multicolor.)
• Use card effects: Play two cards from your hand, then use their effects in the order of your choice to gain gems, ore, or points; convert gems to wild gems, gems of a different color or points; roll the die for a random benefit; gain a card from the creature row; or do other things. You then place the card with the lower number in your discard pile and remove the card with the higher number from the game.
• Acquire artifacts: Discard 2-4 gems or exactly three ore to claim one of the artifact tokens on display, placing this artifact in one of the two storage rows on your personal player board. You can acquire up to two artifacts a turn, and a wild artifact always costs any four gems (or three ore) and can be placed in the wild artifact space (the only way to fill it) or in the position of a colored artifact.
At the end of your turn, you can spend 2-5 artifacts to gain 3-15 points and acquire a rune stone, with each of the eight rune stones having a different power that changes your abilities in the game.
The rune stone powers are cool and all, but your focus in the game needs to be on acquiring points, so while it might feel unnatural to burn through your deck, you must do in order to acquire gems, then artifacts, then points. The game ends the round that someone has at least 65 points, so you need to keep that target in mind, being careful not to burn out too quickly or else you'll have almost no buying power to kick the engine into gear again.
In essence, Rune Stones is akin to a movie scene in which you're tearing apart a steam train to feed bits to the engine to make it go even faster. Feed the engine too quickly, and you'll have nothing left to keep you going; fee too slowly, and someone else will reach the finish line first. Yes, you still score for leftover artifacts at game's end, but in my four playings on a mock-up copy from Queen Games, no one has come within ten points of the winner after adding in those final points. One player got their engine purring at just the right pace, and the rest of us need to keep trying to see what we can do better next time.
You'll find more details about the game in this overview video: