Other game mechanics have been overhauled and updated. For example, players can tether multiple objects together with the grappling hook and can increase the amount of available tethers by activating in-game 'mods', which are earned by completing challenges. Parachuting is also more stable and allows players to shoot enemies from the air. The player can grapple nearly every object and non-playable character in the game with the grappling hook. In-game currency has been left out of Just Cause 3, making supply drops more easily accessible. However, this affects the game's difficulty; for example, if the player chooses to ride a tank, the enemy AI matches the power of it and adopts weapons that are able to take down a tank. Another new feature is giving the character an infinite amount of "GE-64", a Bavarium-based planted explosive similar to C4. Players can deploy three units of GE-64 at a time, and up to five with the in-game 'mods'. In Just Cause 2, players were able to stand on top of moving vehicles but only in the center; in Just Cause 3, players are allowed to move around freely on vehicles. Players are expected to liberate hostile military bases and towns featured in the game, which thereafter can be used as fast travel locations.
When designing the game's world, the studio collected photo books of the Mediterranean area and sent a team to several Mediterranean islands to get a better glimpse of the area. The environment of the game is inspired by the landscape of Monaco and the southern Mediterranean area. Avalanche Studios considered such areas "an untapped resource" which no other developer had worked on before. In order to portray a world under dictatorship, the developers of the game established a color scheme composed of mainly grey, yellow, and red, to convey a sense of oppression. The size of the game's world is similar to that of Just Cause 2, but Avalanche promised that the content featured in the world would be "denser" than its predecessor. Environmental destruction is expanded in Just Cause 3, as Avalanche considered it a key element in creating a cinematic experience and a mechanic to give players more freedom. The team also considered that with the advancements in technologies, they were able to add more destruction mechanics, which are of larger scale, to the game.
Girls und Panzer-themed mods for the game were announced at the 2013 Tokyo Game Show; these game mods were distributed as free downloads for players in the South-East Asian server, mainly targeting the Japanese-speaking community. Initially, there were six voice packs released, featuring the voices of all five members of the Anglerfish team, as well as a special voice pack for Nonna, the vice captain of Pravda's sensha-dō team; each of the five crew members of the Anglerfish team voices the five different crew positions in World of Tanks: Commander, Gunner, Loader, Radio Operator, and Driver. The voice packs replaces the standard crew voices with the Girls und Panzer character voices, when tank commands such as "Target acquired!" or "Reloading!" sound in the game. The voice packs, however, are only available in Japanese. Afterwards, a garage mod was released, where players could change the regular game garage to the sensha-dō garage square in Ōarai Girls High's Academy Ship. Another mod that was released allowed players to change the skins of a few select tanks in the game to the paint jobs of the tanks in the Girls und Panzer anime. Tanks include the Panzer IV H of Ōarai Girls High, the Churchill VII of St. Gloriana Girls Academy and the Jagdtiger of Kuromorimine Girls High. The last mod that was made available changed the look of destroyed tanks for certain vehicles; instead of a smoking wreck of metal that is shown when a tank is destroyed, the tank is shown in a moderate condition, with a white flag on top, similar to when tanks are knocked out in Girls und Panzer, to indicate that the tank is destroyed. 2b1af7f3a8