A.R.S.E.N.A.L is a shareware real-time strategy game that is in many aspects similar to Dune II and Command & Conquer. Gameplay elements include base construction, resource gathering and large-scale combat with ground, naval and air units. The game also introduces several unique elements to the genre: for example, all vehicles consume fuel, and the players need to maintain a supply network of gasoline trucks to keep their forces operational. Units also gain experience in combat, and this places an emphasis on micromanagement, encouraging the player to protect and repair damaged units, rather than rely on waves of expendable forces.
There are three single-player game modes in A.R.S.E.N.A.L: tutorial, campaign mode and custom game. However, there is no multiplayer. The tutorial consists of 10 missions which progressively increase in difficulty, intended to introduce new players to the basics of the game. It is necessary to play through the tutorial first to unlock the two other modes: completing the three first tutorial missions gives the player the ability to play custom games, and to play the campaigns the player must first achieve the rank of Captain in tutorial mode. There are two campaigns, each 10 missions long, which are considerably more difficult than the tutorial campaign.
The story of the tutorial and the campaigns is set in a fictional alternate history World War II where an alliance of European nations fights against Communist invasion. Custom games are played on randomly generated maps, with five factions available for play: Normo, Psycho, Shyzo, Parano and Fanato. Each faction, with the exception of Normo, has a unique special weapon, otherwise all of them share the same technology tree. In the custom game mode, it is possible to play with computer controlled allies, and also set alliances for computer players.
A.R.S.E.N.A.L supports a range of high-resolutions modes, changeable during play. The registered version features a CD soundtrack, but the shareware version does not have any music. Additionally, saving and loading games is disabled in the shareware version, and the player does not have access to higher-level units and technologies.