You do not need to register anywhere, no.
1. Go to the game's page, eg
http://www.abandonia.com/en/games/74/
2. Click on
3. On the next page, click on
again.
4. Your download should begin now. After it starts, the download page will be replaced with a donation request our owners have placed there. You do not need to donate if you don't feel like it.
Keep in mind that
1) Not all games are downloadable.
a) If you see a "BUY IT", this means the game is still sold. These links send you to a store selling it.
b) If you see an "ESA PROTECTED: NO GO", this means we used to offer the game for download but have been sent a request from the current rights owner to remove it (often accompanied by a more or less polite legal threat).
2) Some download links direct you to other websites (such as Reloaded.org) rather than to the download page on Abandonia itself.