Really, the first 'World War' was actually World War II, which saw widespread fighting not just in Europe but South-east Asia, China and the pacific, whereas World War I from this perspective looks like a primarily European conflict, with all key fronts in Europe. As for other wars before World War I that involved countries across the world, the Seven Years War affected India, Central Europe, the Caribbean, the Philippines and North America. Its participants included Russia, Sweden, Britain (and in that time their American colonies), France, Prussia, Austria and Hanover. There was also the Napoleonic Wars which affected all of Europe, the US, Latin America, and even Syria and Egypt.