- All doors will have HP and can be destroyed. However, this will be disabled by default, and map author would have to enable it via engine mark.
- Maps made in PB2 will work in PB2.5.
- Custom lamp colors.
- New textures and decorations.
- Friendly fire and team damage factor can be configured individually for every team in maps in PB2.5.
- Moving lights/lamps are possible. 
- There will be a Skin Editor. It allows to mix different characters' limbs, as well as recolor them.
- Water will be 3D and will have more realistic splashes. However, it will remain static, meaning it can't flow down to another area by physics laws.
- The game will now display the exact amount of damage dealt by each shot. This can be turned off in game settings.
- Some community-created content will be added later on.
- A coop Campaign has been confirmed. 
- Indirect illumination & sun light effects. Ambient lighting completely removed.
- Dynamic lighting has been added to every bullet, grenade, explosion, muzzle flash, as well as swords. These can all illuminate dark areas. Explosion light is based on explosion color.
- Player bounding box (AKA hitboxes) improvements have been added. They should let player's movement feel more based on player's body instead of the bounding box.
- A "blaster" effect for projectiles.
- Projectile spawn offset instead of spread for certain weapons. This means that bullets, instead of coming from the middle of the player, actually spawn at the barrel of the gun.
- All projectiles have hit points now. Damage needed to destroy projectiles depends on guns: for example, the Assault Rifle C-01r needs 3 hits, and the Pistol C-01p needs 2 hits to destroy rocket. Beam weapons do damage to rockets/plasma/grenades/bullets without knockback. Explosions damage hitpoints and change speed and direction of projectiles (including bullets).
- Bullet-bullet intersections. This allows bullets to interact with one another. However, the bullets are not destroyed. Other projectiles can interact with each other as well.
- A Clan system has been confirmed.
- More than 16 different kinds of swords. Each sword has different stats, such as damage, rate of fire, range etc.
- The pre-v1.17 Alien Pistol will return as its own weapon.
- At least one new game mode, Team vs Team. This is likely the a credits-based game mode that is planned as a second main mode for Multiplayer. In this mode, the players are expected to be able to buy weapons (and likely ammo) using money they have earned by killing enemies (or/and completing some special objectives). It's not clear how exactly this system would work.
- Jetpacks, or at least some jetpack/booster-like equipment/items/abilities. Although it's unknown what would jetpacks look like and what exactly would they do, it's known that selfboost technique will somehow be considered a jetpack, along with double jump.
- When switching between weapons, there is now an animation of a character putting a weapon on their back, then taking out another weapon. The heavier the weapon, the longer the switch takes.
- Ammunition. The map maker can decide which ammo type to use, whether it be infinite, cooldown, limited, or unlimited with reloading.
- Magazine weapons now have reloading animations.
- Throwable grenades are returning.
- AI optimizations and trajectory predicting for grenade launcher-like weapons.
- AI players are now able to make ricochet shots that can hit opponents hiding behind impenetrable walls.
- AI can calculate possible damage for penetration-based weapons in PB2.5.
- AI in PB2.5 can perform wall-jumps.
- AI can swim.
- Al players can use jetpacks.
- AI players can gather information from other allies and make blind shots on targets.
- AI can throw grenades now, and can dodge explosives.
- AI can do blind shots with rocket/plasma/grenade weapons expecting to deal indirect damage to enemy with explosion by aiming at wall near enemy.
- AI are able to use the X button to dodge enemy projectiles.
- Advanced pathfinding for AI, allowing them to move upwards at will or travel the map. 
- Pistols can be dual-wielded. This seems to cause major balancing issues, though. Other weapons can be dual-wielded in the level editor, depending on map author's preference.
- Added collision check for projectiles and weapons. Bullet damage/speed will no longer decrease on gun collision.
- Bullet drop, which affects both bullet weapons and energy projectile weapons.