What 2D/3D engines and game development SDKs are available that run natively on Ubuntu?
Please limit one engine/sdk per answer - and include why you enjoy the engine/sdk.
It has a C++ interface too and it's quite powerful. There might be some Ubuntu packages in a PPA available, but i recommend to download the source code and build it manually.
This is one of the most professional Open Source 3D engines available. It is a bit difficult to set up, but it is rather powerful. The standard API is in C++ but there are bindings for several other languages.
More info here: http://www.ogre3d.org/tikiwiki/Home
Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer. It is used by MPEG playback software, emulators, and many popular games, including the award winning Linux port of "Civilization: Call To Power."
SDL supports Linux, Windows, Windows CE, BeOS, MacOS, Mac OS X, FreeBSD, NetBSD, OpenBSD, BSD/OS, Solaris, IRIX, and QNX. The code contains support for AmigaOS, Dreamcast, Atari, AIX, OSF/Tru64, RISC OS, SymbianOS, and OS/2, but these are not officially supported.
SDL is written in C, but works with C++ natively, and has bindings to several other languages, including Ada, C#, D, Eiffel, Erlang, Euphoria, Go, Guile, Haskell, Java, Lisp, Lua, ML, Objective C, Pascal, Perl, PHP, Pike, Pliant, Python, Ruby, Smalltalk, and Tcl.
SDL is distributed under GNU LGPL version 2. This license allows you to use SDL freely in commercial programs as long as you link with the dynamic library.
Installing sdl library in ubuntu