The two ways of playing
A browser game runs through a supported web browser. Ikariam, OGame and Farmerama are examples in this catalogue. An installed PC game uses its own software or launcher. Enlisted, War Thunder and World of Warships do not become browser games when you install a different browser. Always use the official platform and requirements listed by the publisher.
What to check on your computer
For an installed game, compare the operating system, processor, memory, graphics hardware and storage requirements. A game having a PC version does not mean it supports every computer. For a browser game, check supported browsers, account requirements and any browser settings the publisher recommends. A stable connection can matter for both.
Opera GX is an optional companion
Opera GX can be used for web browsing, guides, videos and supported browser games. GX Control offers limits for the browser's own CPU and RAM usage. These controls are not game settings, do not upgrade your hardware and do not guarantee better frame rates. Lower browser limits may also affect the responsiveness of tabs. You do not need Opera GX to use Favorite Games or register for the games here.
Keep your first setup simple
Choose the game first. Install only the software its official instructions require, and avoid downloading tools merely because they appear alongside a game recommendation. Test your current setup before changing several settings at once. If you try a new browser, assess its usability and resource usage for your own workload, separately from the game's performance.