Aligning with the Industrial Revolution 4.0, an abundance of high-tech inventions has embarked their pavements in the educational field. Despite being under the 21st-century umbrella, the English language proficiency of Asian learners is still a few steps behind. Undeniably, most of the English as a Second Language (ESL) learners in Asian countries face challenges in learning ESL grammar. Grammar has been an intricate component to master due to its nature of complexity. This study aimed at exploring the effectiveness of using online language games in improving ESL learners' grammar. A total of 30 students in a secondary school were involved in this research. The research design of the quasi-experimental method was used, employing the pre and post-test. Data were analyzed using percentages to compare the results after three interventions of gamified-learning known as Socrative, PowerPoint Challenge Game, and Kahoot! The main findings indicated that learners' scores on the grammar post-test showed a significant increase from the pre-test. The improvements can be seen in the grading system, whereby, no participant obtained a grade D and E in the post-test as compared to the pre-test. Hence, the results depicted that gamified-learning is effective in teaching grammar to ESL learners.