Genestealer player may have the objective of destroying a specified Terminator piece or all of the Terminator pieces or some other objective. The pieces of the two players move at different rates (Terminators move slowly, Genestealers rapidly). Terminator pieces excel at ranged combat, but are weak in close combat; the Genestealer pieces excel at close combat, but cannot perform ranged combat at all. The pieces are moved by the players through a system of "action points", where each piece has a certain number specified for it. A Terminator piece has few action points; a Genestealer piece has many action points. The game is notable for its hidden play mechanics, from which it derives much of its playability and tension. On the one hand, the Terminator player has a variable number of "command points" available each turn which are only revealed to the Genestealer player after they are used up; these command points may be used to move the Terminator pieces either during the Terminator player's own turn or during the Genestealer player's turn. (In the second edition, the extra points were not hidden from the Genestealer player.) On the other hand, the actual number of Genestealer pieces in play is hidden from the Terminator player, because the Genestealer pieces come into play as "blips" which may represent multiple creatures. (1-3 creatures in the 1st 3rd and 4th editions; 0-6 in the 2nd edition; 0-3 in the Deathwing expansion; and 1-6 in the Genestealer expansion.) In the basic version of the game, playing as the Terminators can be engaging and tactically challenging, partly because the Terminator player is constrained by a time limit for their turn, while playing as the Genestealers can be very straightforward. To overcome this asymmetry, players are encouraged to play each mission of the game twice, swapping between playing with Terminators and playing with Genestealers. The fairly fast play time (around half an hour per mission), driven by the Terminator player's time limitation, makes this feasible. The Deathwing expansion pack for the first edition included rules for playing the game as a one-player game—that is, playing the game as Terminators using different mechanics for moving the Genestealer pieces. The Genestealer expansion pack for the first edition included rules for human-genestealer hybrids, which could carry weapons and equipment, and for a Magus and for a Patriarch, adding more depth for the Genestealer player. However, these additions were not