The game was released for Windows, macOS and Linux in February 2020 at the conclusion of a five-year long early access phase that started in January 2015.

[3] An update in December 2017 added a level editor and multiplayer capabilities, such as pitting the vehicle creations against each other, or other players attempting to knock down a castle created by another.

[4] With these additions, players developed systems to run tournaments similar to the television show BattleBots, pitting their Besiege creations in one-on-one matches with others to try to take the other out.

The Splintered Sea adds water physics and buoyancy mechanics to the game, with 10 new maritime levels and new blocks allowing players to build sailboats or submarines.

[9] Rock, Paper, Shotgun later published a review of the release version by Jay Castello, who admired the game varieties that kept her engaging and trying to construct the new better siege engines.

[11] PC Gamer article by Rick Lane gave the game 85 out of 100 and said: "Besiege lets you build siege weapons in a medieval fantasy realm.