The free demo is "free to keep" and allows you to participate in the game's massive multiplayer battles indefinitely, though with specific limitations:
: Access is restricted to Enlisted and Officers of the 13th Virginia and 20th Maine regiments, plus their Color Bearers.
While the full version of is a paid title, you can legally download a free, non-time-limited demo on Steam that includes multiplayer access. Free Demo Features
: Support for up to 300 players (and occasionally up to 500 in testing) on a single battlefield.
: Even in the demo, you can access modded content like the Age of Napoleon or Space Eras. Full Game Overview
: You cannot play as other regiments, nor can you use Artillery, Engineers, or the Ambulance Corps.