Star Munchkin is the first standalone sequel to Munchkin. Both games play by nearly the same system, although the terms used to describe the game have changed. For example, what was a "door" card in Munchkin is a "station" card in Star Munchkin.
The game components consist of two decks of full-sized cards: one deck of station cards and one deck of treasure cards. There is also a standard 6-sided die, which is infrequently used.
The basic rules of the game are simple. The object is to level up to 10 experience points. On their turn, a player may draw a station card. A station card could be a monster, trap, or other various cards. If it is a trap, certain deleterious effects described on the card immediately befall the player. If it's a monster, combat ensues. Otherwise, the player takes the card. Then, if the card was not a monster, the player may "loot the room", taking another card from the station deck and placing it in their hand, even if it was a monster or a trap. Traps can later be played out of a player's hand to affect other players. Monsters can be played on a player's turn instead of drawing a station card, to guarantee a fight.
Combat is in principle very simple. The player adds up their strength, including any bonuses from equipment, and compares it to the monster's strength. If the player is stronger, they win and receive one or two experience points and are instructed to draw a certain number of cards from the treasure deck. If they lose, "Bad Stuff" befalls them, unless they can run away with a lucky die roll. The "Bad Stuff" is described on the monster's card, and ranges from minor to "You are dead," but "You are dead," does not mean elimination from the game.
Two wrinkles make combat interesting. First, you or other players can play cards from your hand that modify the battle. The most common variety modify the player's strength or the monster's strength. Second, one other player can volunteer to help you fight. There isn't usually a built-in incentive for any player to help you. The rulebook recommends that you negotiate. Negotiation usually involves offering the helping player a share of the loot you stand to gain from winning the battle. Frequently, an informal auction erupts, with players bidding lower and lower asking prices to be the helper. With my group, it's usually possible to find some help unless no one is strong enough, or the group perceives you as the leader.
The rules in the rulebook are very simple, but most of the rules are in fact on the cards. Many cards have special text that describes what they do.
The fun in the game, besides the humorous sci-fi parodies and art, is mostly in what is called "Munchkinly" behavior. Munchkinly behavior is acting in a generally unexpected and underhanded way. Often this revolves around combining or exploiting the card text in creative ways. For example, a player may apparently generously offer to help you in a combat, then play a card to help the monster that requires that they play it during a combat they're involved in. They only offered to help so that they could get in the combat and play the card. Suddenly, you're losing the battle again, and can't ask for any more help. You lose, but the player helping you uses another card to get out of the bad stuff, but you're left stuck with it.
The game's weakest point is the victory condition: getting to level 10. What typically happens is that players save their negative cards until the first time a player at level 9 fights a battle. Although they could play them earlier to delay the player getting to level 9, it's not much of a disadvantage to wait. Also, every level but the last can be bought by selling off items or come free with a card. The last level is the toughest hurdle.
Then, players play most or all of their negative cards against the first player who attempts a battle at level 9. The next player who makes the attempt often has an easy time of it, or the third.
Still, this is a light and not very strategic game, and players should not be very concerned who wins, even if it is not the best player.
Although nearly the same game, I slightly prefer Star Munchkin to the original Munchkin. The play time for Star Munchkin seems to be faster.
For me, this was a sort of "pre-gateway" game. Although it isn't a Euro-game, it was my introduction to non-mainstream games. The same person who introduced my group to Munchkin, after its success, introduced Carcassonne. We then discovered BGG and what else was out there. Star Munchkin doesn't hit the table much anymore, but it's just because we usually find something better to play, not because it isn't a good game.
An extremely accurate review, I feel, for just about every Munchkin