When I was young, Xcom used to be one of my top games along with Koei’s Three Kingdoms. Over the last few years, an open source version of x-com named openxcom is released (http://openxcom.org/). It like back to the old days for me. The installation comes a little tricky and I have some notes below. Hope it helps.
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Installing OpenXcom on *buntu Linux
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using ppa

$ sudo apt-add-repository ppa:knapsu/openxcom
$ sudo apt-get install openxcom
$ cd ~/.local/share/openxcom
$ mkdir data
$ cd data
$ cp -r path/to/vanilla/xcomufo/ .

download universal patch and unzip to ~/.local/share/openxcom/data

$ openxcom

note: config file is in ~/.config/openxcom/…. (options are http://ufopaedia.org/index.php?title=Options_(OpenXcom))
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using wine (limited working)
download openxcom windows installer
unzip and run with wine
this should work but apparently it crashes with errors
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using gitclone (not working)

$ cmake -DCMAKE_BUILD_TYPE=Release ..
$ sudo apt-get install libyaml-cpp-dev
$ #sudo apt-get install libsdl-image1.2-dev
$ sudo apt-get install libsdl-gfx1.2 libsdl-gfx1.2-dev
$ sudo apt-get install libsdl-mixer1.2-dev
$ sudo apt-get install libsdl1.2-dev libsdl1.2debian
$ sudo apt-get install mesa-common-dev mesa-utils-extra libgl1-mesa-dev libglapi-mesa
$ sudo apt-get install build-essential cmake checkinstall
$ sudo apt-get install libsdl2-dev
$ sudo apt-get install xorg-dev
$ #sudo apt-get install libudev-dev libts-dev libglu1-mesa-dev libasound2-dev libpulse-dev libopenal-dev libogg-dev libvorbis-dev libaudiofile-dev libpng12-dev libfreetype6-dev libusb-dev libdbus-1-dev zlib1g-dev libdirectfb-dev xorg-dev

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Vanilla XCom
This can be downloaded and run using dosbox at http://www.myabandonware.com/game/x-com-ufo-defense-1pl
unzip the download

$ sudo apt-get install dosbox
$ cd path/to/my/unzipped/folder
$ dosbox xcom.exe

(recommended) I suggest a copy with xutils if you can find one. Alternatively, Steam also offers downloadable versions of XCom. Or you can purchase from Amazon.

Amazon Purchase Link