Bookworm Adventures follows the tale of a little green worm named Lex (of the original Bookworm game) throughout 3 themed books as he spells words to defeat evil monsters. The main game interface is a 4x4 grid of letters, and unlike in the original Bookworm game, the letters do not need to connect to form words. The game is turn-based, and after the user attacks their opponent, the opponent then takes its turn. Each book is divided into 10 chapters that culminate in a "boss battle" in which the player is rewarded with a treasure upon defeating the enemy. Treasures do many things, ranging from increasing damage for using certain letters, to stunning the enemy, and a whole lot more. A player can only choose 3 treasures to bring with them into a chapter (out of an eventual total of 31).

The game is part RPG, part word game. Eventually, the player will find that enemies can cause status ailments such as poison, bleeding, burning, stun, petrification, etc. These range from causing damage over time, to loss of a turn, to weakening their attacks. Through the use of certain treasures, items and special gem tiles, the player can cause similar inflictions to the enemy. In addition, after defeating a monster the player is awarded experience points, which will lead to a level up which imparts a bonus of either extra health, attack power increase, or defensive ability increased.

The player is rewarded with gem tiles for spelling words of longer length (and also by using certain treasures which increase their frequency of appearance). Enemies will also sometimes drop potions. Health potions refill the user's health meter, attack potions increase their attack power by 50% and purify potions clear the player and tile grid of all status ailments.

The game also includes an Arena mode (unlocked after completing all 3 books) in which the player can fight in real-time against all the bosses of the game. Every 5 opponents, the player is awarded one of each potion type and is allowed to change the 3 treasures they have equipped. Players are rewarded for spelling lots of short words quickly, attacking first, attacking many times before an enemy gets an attack in, defeating the opponent in 1-3 turns, and more. The more of these awards the player gets, the more bonus experience points they gain.