Lock's Quest is a 2008 real-time strategy tower defense video game developed by 5th Cell and published by THQ for the Nintendo DS.

Players control Lock, a young man forced to help defend the kingdom of Antonia from an invasion of clockwork soldiers.

The game was positively received upon its original release in 2008, with critics particularly praising the plot, gameplay and graphics.

In 2017, a remaster of Lock's Quest was released for PC, PlayStation 4 and Xbox One, and in 2019 was ported to iOS and Android mobile phones.

Lock's Quest is a real-time strategy game, incorporating tower defense gameplay elements.

During the Build phase, the player has a limited amount of time and resources to construct defences, which consist of walls, towers, cannons, machines, and traps.

The player can also use Lock to repair damage done to defences, which requires another quick time event called "ratcheting".

Seeking vengeance upon the King, Agonius assumed the mantle of Lord Agony and created a clockwork army with the intent of destroying the kingdom.

The exact nature of the events that happened therein are not revealed until the end of the game - all that is known, at first, is that Agony was defeated, and Jacob was missing, presumed dead.

Lock is a young man living in the coastal village of Seacrest, along with his sister, Emi, and grandfather, Tobias.

THQ revealed the development of a tower defence game with the working title Construction Combat: Lock's Quest in April 2008 in a press release.

[7] In July, at San Diego Comic-Con, THQ debuted a promotional mini-comic based on the universe of the game entitled Lock's Quest: A Source of Hope - Volume 1 drawn by Edison Yan.

[9] As promotion for the game's release, 5th Cell held a competition to win a custom DS Lite on their website.

[2][19][20] Nintendo World Report said Lock's Quest was "just a few design tweaks away from being a fantastic game", claiming that it is "definitely disappointing in light of all its great assets and originality".

[3] Eurogamer criticized the battle phase of combat and the enemy artificial intelligence, while praising the "excellent graphics and repetitive but gripping gameplay".

[21] Nintendo World Daily praised the "wonderful sprite graphics" as well as "great animation and a clean, colorful look".