RuneScape is free to play, and as a free player you are allowed to access F2P worlds, and can max out all of the skills that are open to free players. There's no limit on the level you can get in those skills. However, free players are restricted in terms of the quests that they can do, the areas they have access to, and the list of skills that they can train. They are also not permitted to log on to the P2P worlds. The world limitations make it more difficult to make money, but it is still possible to get rich if you can identify the items that are most in-demand on F2P worlds.