During last Ludum Dare there were some participants who weren’t aware of the rules, especially not of the restrictive rules of the 48 hour compo. Yes, it is a fun competition, but the restrictive rules are part of the fun. Participate in the Jam if the rules are too restrictive for you. Having to argue about violated rules afterwards is always awkward, thus here a quick reminder: Read the rules!
The most important restriction some weren’t aware of: ALL content must be created within 48 hours! This means you are NOT allowed to use graphics, sounds or music previously created by you or others. You are NOT allowed to use downloaded graphics, sounds or music, even if they are free and even if you modify them heavily! The only graphical third-party content you are allowed to use in your project are Fonts. The only third-party audio elements you are allowed to use are drum loops, drum samples and sampled instruments used for music creation.
You are, however, allowed to use Content generators that create graphics, sounds or even music on-the-fly based on parameters given as input. sfxr is a popular example.
The same basically also goes for code, but you are allowed to use all publicly available frameworks and libraries. You are also allowed to use generic base code and personal libraries IF you make them publicly available prior to the start of the competition by posting them here on the site (as a blog post). This exception is probably in place to lessen the advantage of game creators and full-blown game engines over entirely self-written games.
With that being said, have a lot of fun by challenging yourself, be it in the 48-hour-compo or the 72-hour-jam!