Dragon Warrior Monsters, known as Dragon Quest Monsters: Terry's Wonderland (ドラゴンクエストモンスターズ テリーのワンダーランド, Doragon Kuesuto Monsutāzu: Terī no Wandārando) in Japan, is the first video game in the Dragon Quest Monsters series. It was released in Japan by Enix on September 25, 1998, and co-published by Eidos Interactive in Europe in 1999 and in North America in 2000. It was the first Dragon Quest game to be released in Europe. It was released for the Game Boy Color before the console itself was released; however, the cartridge is backward compatible with the older Game Boy console in black-and-white color. The game was remade for the PlayStation as Dragon Quest Monsters 1+2 (ドラゴンクエストモンスターズ1・2 星降りの勇者と牧場の仲間たち, Doragon Kuesuto Monsutāzu Wan Tsū: Hoshi Furi no Yūsha to Bokujō no Nakamatachi, lit. "Dragon Quest Monsters 1 2: The Hero From the Stars and the Rancher Friends"), a hacker and translator going by the names of Kingcom and Tom are currently working on a complete English translation patch for the game. The patch will be available upon completion on their website. A mobile phone incarnation titled Dragon Quest Monsters i was released in Japan on January 28, 2002.

The game features the characters Terry and Milly from Dragon Quest VI when they were children, before the events in Dragon Quest VI. Dragon Warrior Monsters is often compared to the Pokémon series due to their similar gameplay. Critics set the games apart by noting the in-depth breeding system seen in this game.

Square Enix announced at the Tokyo Game Show in 2011 a re-release of the game for the Nintendo 3DS.

The game follows Terry as he attempts to save his sister. Instead of fighting in battle, Terry is able to recruit monsters into his party. When fighting random battles, Terry can set out meat, which may coax the monster into joining the party at the end of the battle. Terry can also breed two monsters, combining them into a new, stronger monster. Excess monsters can be placed on the Farm, a storage place for monsters. They can be picked up or dropped off and there is an option to put monsters at the farm to sleep, which allows them to maintain their wilderness level, but not grow in level. There can be 19 awake and 19 asleep monsters at any one time. A monster's wilderness level lowers as Terry trains them, which makes them more likely to participate in battle. By leaving monsters at the farm awake, they become more wild.

Just like in most RPGs, monsters are able to gain experience points and level up after battles. Each monsters' requirements for experience points to level up varies, depending on their plus number or even what monster family they belong to. When they level up, they gain stats and sometimes skills. All monsters can carry a maximum of eight skills; if a monster can gain more than eight skills you have the option of replacing old skills with new ones.

The player moves around to other worlds through warp gates which are located underneath the throne room. To access these gates, the player needs to defeat a certain class ranking. There are a certain number of areas in a world and at the last one, the player needs to defeat a boss. Some bosses in the game offer to join the player's party automatically, some have to be won over with meat, and some will not join at all. Other gates are hidden throughout Great Tree, such as one in the library that is only accessible after befriending over 100 different monsters.

In this game the player fights in the arena and goes through ranks that consists of three different battles that must be won before the player can advance to the next ranking. Each rank provides harder challenges: the higher the rank, the harder the monsters. The battles you able to start at are from Rank G and go to Rank D and later in the game you are able to go from Rank C to Rank A and then Rank S. These battles open up gates for the character to explore and are necessary to progress through the story.

Tiny Medals are scattered throughout different worlds randomly and are picked up by the player. In the game, there is a man who collects these medals, who is later revealed to be the king of Great Tree, and will give certain monster eggs for how many the player gives to him. Also, Foreign Masters may appear while in other worlds. These encounters with other trainers can result in battle. There are different types of trainers that will give or do something for the player if they are defeated. These trainers monsters may also join you if you give them meat.

The game also comes compatible with the PlayStation's i-mode adaptor, allowing players to upload monsters from the game onto the mobile phone version of Dragon Quest Monsters.

Breeding

After beating Class F in the Arena, the player can breed monsters if they are at level 10 or above at the Shrine of Starry Night, which is taken care of by the current Master Monster Tamer. Breeding requires one male and one female monster. The result of the breeding will be an egg, containing a level 1 monster which has characteristics of both parents, including skills and stats. The egg can then be left in the monster farm or hatched, which costs a small fee. The monster born will have a plus number next to it, the number generally signifying the greatness of the monster's stats, the higher being the better. It costs more money to hatch a monster with a higher plus number than one with no plus number. Also, the number beside the plus multiplied by two is added to the limit for the maximum level for the monster.

Once the Egg Evaluator is available for use, eggs can have the gender of the monster they're containing checked and changed. Both requires a small fee which is paid to the Egg Evaluator. The fee increases depending on the monster's plus number.

A monster that was created through breeding has much higher stats and many more abilities than a monster that was found in the wild, thus it is much harder to complete the game without breeding many generations. Breeding is also the only way to acquire certain monsters. Also, the monsters that bred to make the egg leave you.