Linux Simulation Games
Below are a few screen shots, and a list of games in the Simulation section:
 

BZFlag

GL-117

Search and Rescue

Airbus A340 Glass Cockpit project is an intiative of the IRADIS foundation. It uses the glass cockpit library libGC developed for this project, which provides an open interface to the rest of the flight simulator and contains a framework designed for easy development of a glass cockpit.
 
BZFlag is a 3D multiplayer tank battle game that pits players against each other in a networked environment. It runs on Linux, Windows 95/98/NT/2000, Irix 5.3 or higher, and Solaris. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
 
Celestia is an OpenGL-based 3D space simulation for Unix and Win32 that lets you travel through the solar system, to the stars, and even beyond the galaxy. Visit over 100,000 stars, 100 solar system bodies, and all known extrasolar planets.
 
Collapsar Creations Project 1 is a cross-platform space simulation game. It will have multiple single-player and multiplayer modes, with an open architecture and a complete toolset to produce new content and code.
 
Dopewars is a UNIX rewrite of the MS-DOS program of the same name, which in turn was inspired by John E. Dell's "Drug Wars" game. You have one month to buy and sell drugs on the streets of New York, the aim being first to pay off your debt to the loan shark and then to make a fortune. And if you have to shoot a few cops in the process, well... The game includes TCP networking allowing you to meet (and shoot) other human drug dealers. Computer drug dealers are currently in development.
 
FACHODA Complex is a fast 3D game for X11 with network support. It has soft rendering, but is still quite fast. A Pentium with MMX is required.
 
FooBillard is a billards (pool) SIMULATIon under Linux/OpenGL.
 
Free Reign is a fully-3D city simulator, with advanced features planned such as ore mining, advanced financial models, and other features users request.
 
GL-117 is an OpenGL- and SDL-based action flight simulator written in C++. It provides a random terrain generator, lighting effects, sounds, and joystick support.
 
GRacer is 3D motor sports simulator. The physical simulation engine calculates the forces for each wheel. It can reproduce very realistic behavior like drift, wheel spin, and even accelerated turns.
 
LinCity is an SVGALIB (Linux only) and X based city/country simulation game for Linux and other Unix platforms (Solaris, FreeBSD, HP_UX, AIX, SCO and IRIX). There is also a Win32 version (win95 and NT) available as a separate package. The game reminds a bit of SimCity but has it's own goals and methods to get there.
 
LinuxSSN is a naval combat simulation game. It is based on the operations of a nuclear submarine.
 
Mars Simulation Project is an open source Java project to create a simulation of a future human settlement on the planet Mars.
 
Open Pinball is a pinball simulator. The program is divided into two processes. The main process takes care of interpreting the .table description files and controls the ball's movements according to physical laws. It communicates the ball's coordinates to another process (renderer) which renders the table (taken from the same .table file) and the ball as it moves around. The main process must also communicate status for objects it hits so that renderer can produce sounds and count scoring. The rendering process is currently a 2D renderer.
 
Pizza Business is a console-based game written in object-oriented C++.
 
RealTimeBattle is a programming game, in which robots controlled by programs are fighting each other. The goal is to destroy the enemies, using the radar to examine the environment and the cannon to shoot.
 
Search And Rescue is a game in which the player pilots rescue helicopters to rescue victims in various situations of distress.
 
Space Mines is a game where one needs to make money by building mines and by keeping one's workers happy.
 
Spectemu is a fast and nearly perfect emulation of the 48k ZX Spectrum computer. It can be run in an X11 window or on a Linux console. Features include sound output, tape emulation (with border stripes and sound), snapshot saving and loading, and an interactive keyboard picture.
 
Stoned is a simple but fully functional curling simulation. It features 3D graphics, network play, and funky sound.
 
Sunplasma first creates a virtual world that looks somehow like the real world, and then it lets you fly through it.
 
Trophy is an action car racing game for Linux. It's 2D (top-view) but aims to provide high quality graphics. You can shoot, drop bombs, and drive against the other players.
 
Ultimate Basketball Challenge is a 5 on 5 basketball game for Unix variants including Linux and FreeBSD. It aims to be fully customizable (add/edit teams, players, stats, courts, arenas, etc.). You can currently play against the basic AI.
 
Vega Strike is a Linux action space simulator designed to bring 3d space combat to a whole new level of graphics, gameplay, and customizability.
 
X-Plane for Linux is the Linux port of X-Plane. X- Plane is the world's most comprehensive, powerful flight simulator, and has the most realistic flight model available for personal computers. It comes with subsonic and supersonic flight dynamics, sporting aircraft from the Bell 206 Jet-Ranger helicopter, and Cessna 172 light plane to the supersonic Concorde, and Mach-3 XB-70 Valkyrie. X-Plane comes with about 40 aircraft spanning the aviation industry, and several hundred more are freely downloadable from the internet.
 
XPilot is a graphical multi-player maneuvering game with less-exciting graphics, but more speed, tactics, and insults. Some people also use it for UDP network analysis. Over the past eight years of playing and development, tons of features have been added to the game, from basic weapons like shotguns and missiles to more recent ones like phasing devices, invisibility, or hyperjump.
 
xplanets is a simulator that shows a spaceship moving through the solar system. The spaceship's movements are influenced by gravity from the sun and the planets according to Newton's laws, and by the acceleration that the engines provide. The planets move around is (simplified) round orbits.
 
XShipWars is a massively multi-player, ultra graphical, space-oriented gaming system designed exclusively for network play. You create your own universes, build your own vessels and form your own empires.