A missing DLL is often just the first symptom of a larger installation issue. The Proper Fix
Sometimes files are accidentally dragged away from their game folders.
Since he was using Steam, he right-clicked the game, went to Properties > Local Files , and clicked Verify integrity of game files . This automatically detected the missing ijl15.dll (an Intel JPEG Library file) and redownloaded the official version.
Alex finally had a free Saturday to revisit a childhood favorite: Half-Life . He clicked "Play," expecting the familiar intro, but instead, a cold, grey box appeared:
