RPG games, set in the future after a nuclear fall out, hence the name. You are a vault dweller in the first one that is sent out to find a water processing chip because your vault's chip went bad. The vaults are underground safe houses that kept humans deep under ground to be safe from the hazards of nuclear fall out. so, you roam around and go on quest after quest (more like jobs) collect a bunch of guns and some futuristic weapons, you can get some companions (you get a dog that follows you if you feed it some food) and eventually get some powered armor and fight super mutants. The game itself is hours upon hours of entertainment. It is skill based and every time you level up you can pump more percentage points into your skill sets.
The targeting system is unique. You are allowed to do called shots where it pulls up a grid of the creature and you can choose to shoot it anywhere you want. My favorites are the eyes and the groin. Its humor is very much young adult. You can get addicted to drugs, and when you don't get your fix your stats suffer.
In fallout 2 you are a descendant of the original vault dweller and you are chosen to go out and look for a GECK (garden of eden creation kit) to save your villages land. This one you can get a car, and there are more weapons and more cool things to do. You can play the good guy or the bad guy a lot better in this one. You have what is called karma and if your actions are good you get positive karma and if you are evil you get negative karma. If you get so evil you can threaten people and they actually get scared of you.
Fallout tactics is a real time strategy RPG, completely mission based so you don't get the freedom of the original fallout RPGs. Its fun, and a good story line of the brother hood of steel, which you encounter many times in both fallout 1 and 2.
These games are bargain bin games now, and can probably both be bought for under 10 dollars. I highly recommend you go pick them up.