Assaultcube is a first-person shooter video game designed to be very fast and works on almost any computer and operating system, as it requires very few resources.
We can find it in Debian and the objective of the game is very simple: Play Online with your friends. Although of course, we can also do it alone against some bots. I personally love its graphics, and the recoil when firing a gun is quite realistic, something that is not appreciated in games like openArena, For example. Assaultcube is an excellent alternative for lovers of Counter Strike 
Game modes
- Capture The Flag (CTF. Capture the enemy flag.)
- Deathmatch and Team Deathmatch (DM and TDM. Deathmatch.)
- One Shot One Kill and Team One Shot One Kill (OSOK and TOSOK. Combat one shot to the death.)
- Last Swiss Standing (LSS. Combat with knives for rounds.)
- Survivor and Team Survivor (SURV and TSURV. Combat by rounds.)
- Pistol Frenzy (FP. Combat with pistols by rounds.)
- Keep The Flag and Team Keep The Flag (KTF and TKTF. Capture of own flag.)
- Hunt The Flag (HTF. Possession of flag.)
- Cooperative Edit (COOP. Cooperative editing of a map.)
Weapons available
There are seven weapons, which are available to use at any time.
- Swiss Tech Combat Blade DR-88 (Razor)
- Mk-77 Semi-Automatic Pistol (Pistol)
- MTP-57 Assault Rifle (Assault Rifle)
- Precision Tech AD-81 Sniper Rifle (Sniper Rifle)
- A-Ard 10 Submachine Gun (Submachine gun)
- V-19 Combat Shotgun (Shotgun)
- SAL-T3 Grenade (Grenade)
To install it we open a terminal and put:
$ sudo aptitude install assaultcube
Source: @Wikipedia