Ernie Eaglebeak is a young lad living with his cruel stepfather Joey Rottenwood, who keeps him locked up in the attic. Ernie is secretly in love with his neighbor Lola Tigerbelly, a young woman definitely out of his league. Things take a turn for the better when Ernie gets accepted as a freshman by the Sorcerer University, a prestigious school of magic. At first Ernie is fascinated by college life and meets a few attractive women as well. However, when the magical Sorcerer's Appliance gets stolen, Ernie is sent on a dangerous mission to recover that powerful device. Armed with his spellbook and a magical surfboard, Ernie must cross the Fizzbuttle Ocean and travel to various islands searching for clues.
Spellcasting 101 is the first game created by Legend Entertainment, heralding their hybrid graphical and text adventure format. Continuing Infocom's tradition of humorous text adventures, the game can be played in text-only mode. However, graphical depictions of locations can be activated as well, and the game gives the player the opportunity to combine verbs from a list with on-screen objects in an almost point-and-click fashion. The game contains many puzzles following a peculiar sense of logic; it is also possible to get irrevocably stuck and die.
Magic spells (including such exotic ones as increasing a person's bust size) can be learned and then used in appropriate situations to solve puzzles. The player's actions advance the game's internal clock, and some of the tasks are based on being in the right place at the right time. The islands are tackled as separate scenarios and are self-sufficient gameplay-wise. The game contains many puns and jokes, some of them college-oriented (e.g. Tappa Kegga Bru or I Phelta Thi fraternities). It is possible to activate the "Naughty Mode", which shows the game's female characters semi-naked in some scenes, and also makes the corresponding text descriptions explicitly erotic.