A four-player boardgame of resource management, Space Junkyard is set in, well, a space junkyard; the game is a free PDF, though you'll have to print out the components (I suggest printing onto blank, full-sheet labels, mounting on cardstock, and cutting apart).
The game is played on a 6 by 6 array of tiles, with each tile representing either an asteroid or an abandoned ship part. Each player controls one ship, which begins only with a "bridge"; the bridge can store three of each resource type, and produce one "radioactives" resource each turn. Each ship part is worth some number of victory points (from zero to four), so the ultimate winner is the player who is most successful at collecting ship parts and connecting them to his bridge.
During your turn, you can move your ship three tiles (or, by expending a radioactives resource, six tiles), and collect either two asteroids or one ship part. Asteroids are worth resources, of which there are three types: radioactives, metals, and carbon. Ship parts can be "recycled" for resources as well, with the number and type they produce printed on the part.
Connecting a ship part requires you to have an available opening to connect it to the rest of your ship; your bridge is open only one one side, with other parts having anywhere from one to four openings. In most cases, some number of resources are printed along an opening, meaning that affixing another part to that opening requires you to spend the indicated resources (and, typically, you also pay the resources shown on the opening of that other part). Additionally, at the end of the game, victory points are lost for unclosed openings -- so early in the game, a four-opening part is nice to find, but by the end-game, it's the last thing you want.
Ship parts give you additional capabilities, as well; some can store resources, some can create resources, and some can transform one kind of resource into another kind.
The game includes 32 asteroid tiles and 44 ship parts (not counting the bridges); thus, of the 76 tiles, less than half begin in play. The others are shuffled into a draw deck, and at the end of each player's turn, he draws one, and enters it into the "junkyard" at any edge, pushing all tiles in that row or column one space, Labyrinth-style, with the piece that is pushed out of the area discarded.
As with any good boardgame, Space Junkyard has enough depth that serious gamers will want to play it several times to develop a firm understanding of its strategies; but it's also simple and light enough to work in a game party setting. For a free game, it's an impressive effort.
