A six sided dice game. You only need D6 to play, an intentional game design decision since the Japanese market lacked access to atypical multi-sided dice . A decision table was used to expand possible outcomes but it slowed the game down. In Sword World having a class is equivalent to having both knowledge and abilities of said class. Using Sword World's pedigree, being a game inspired by AD&D 2E, class abilities, feats, and knowledge are intrinsicaly all linked to class level.
There are 8 main class-skills. There are NPC only class-skills, but effectively class-skill are Adventure classes, granting combat ability. Non-combat (NPC classes effectively) grant feats and ability to checks. NPC only combat classes behave like Player classes.
Ranger- An outdoor specialist. Class-skill favors traps, detection, tracking, and projectile weapons. Can't wear heavy armor.
Bard - Requires an instrument. Can use free time to earn money performing or writng spell-songs.
Sage - A info dump class. Every level boosts language abilities and some combat knowledge checks.
Sorcerer - A mage who has penalties for a magical focus.
Thief - Abilities related to stealing and assassination.
Shaman - Elemental magic user.
Fighter - Melee specialist. Armor and weapon selection based on strength.
Priest - Divine magic user. Your god affects spell selection. Some NPC only gods exist.
The first game built for Let's Plays and not core play. Few supplements exist compared to the volume of non-rule related media of novels and Replays. Imagine D&D but no splat books and just Dragonlance novels. Some video games exist.
The magic system is not Vancian but closer to JRPGs, using mana and variable mana rates due to meta magic and spell level. Spells are locked to systems etc.