Both game and film VFX use the same core fundamentals of Houdini. The area that they differ is how the fundamentals are applied. Lets say that you wanted an explosion. For both applications you would need to create a source for the simulation then tweak your simulation and materials settings for your end goal. Here is where it gets more interesting. In film you may need to place it in your scene. Only render the volume in the scene and then bring it into Nuke to composite it. In games you might place a camera above the explosion that tracks it. Then render 32 frames with several lights, used to generate a normal map out of (cheaper than a light map). From these frames you pack the normal, alpha, and emission into a 1024x1024 rgba flipbook. Now in the game engine you create a material that uses your new awesome flipbook texture. This material is applied to a particle system that spawns a few particles. These particles play back the top of the simulation to create the explosion in engine.
The biggest difference that you will find is the techniques that are used for game VFX. Many times we are limited to camera facing cards or simple meshes with a panning material. Houdini can help generate content for games. But think of it as a means to an end, instead of a full solution. Anything that you learn in your Houdini journey can be useful in the future. But there isn’t anything that you need to add extra attention for learning Houdini in my opinion.
Areas that you can pay more attention while using Houdini is principles of art theory. Things like timing, shape, motion, color, etc. Jason Keyser made a nice playlist for some of these concepts applied to games https://www.youtube.com/playlist?list=PLQD_sA-R5qVKVYw3EVuRT7fSJsVukLEhD. These types of concepts will translate anything vfx related and help you in your career.
Now if you want to start playing with Houdini for games check out Andres Glad they have really great videos too https://www.sidefx.com/profile/Partikel/. If you have access to pluralsight, I would highly suggest to follow this course https://www.pluralsight.com/courses/houdini-vfx-games. It will help with how to go from a Houdini sim into a full on explosion in Unreal Engine with screen shake! Make sure to check out the gameshelf SideFX has been making. There are a lot of great digital assets there to help you. If you want to give yourself a challenge you can try to use Houdini each of the monthly sketches here. The current months sketch is destruction. There is still enough time to blowup a statue or two!