Classic which can never be forgotten is just few clicks away.
Thanks to the power of modern computers, we can run old-good DOS games directly inside a modern web browser!
There are numerous websites for that. First of them is js-dos.com featuring such games as "Prince of Persia", "Alley cat", "Dangerous Dave 2", "Pacman", and even Doom and Doom 2! in a nice DOS-like interface.
Another website is archive.org, which tries to do the same with more "scientific" approach, and has much more games (most of which I don't know) although I haven't looked into it yet.
And what are your favourite childhood games? Feel free to write me an email (address at the bottom of the page) - your response, if you like, will appear below here!
Sources: habrahabr.ru, geektimes.ru (both in Russian)
Comment from Anastasia Bengtsson:
Cool, I'll check it out later. Don't you like DOSBox? I've enjoyed playing Prehistoric, the Legend of Kyrandia: Hand of Fate, The Settlers and one more game - a strategy that reminds me a bit of AOE, there were giants, Valkyries, wizards. It was really good, too bad I forgot the name.
I've noticed that you play only old games, isn't it a bit boring? :))
Regarding old games - no, I play new games sometimes, too: I played Fallout 3 soon after it was released - I completed it in 3 days - it was quite happy time in my life. But old games, on contrary, I can't complete that fast.
And now I'm waiting for GTA V to be released on PC, since I enjoyed playing GTA 2 and 3. I also will need to buy a new PC for that, since last time I upgraded it just enough to play Morrowind. :-)