If you are using windows 8/8.1 or 7 go to Start (or click start) choose run and type regedit then hit enter.(You might have to be an administrator on your device for this to work.) Once you have typed in regedit you should be presented with it saying Yes or No underneath where it says, "Do you want to allow the following changes on this computer?" Click Yes and then you should see this pop up.

Now you need to click on the arrow for HKEY_CURRET_USER

Now click on the arrow for Software

Now scroll down to Valve and click on the arrow.

Now click on the arrow for Half Life

Click on Settings

Now find ScreenHeight and find ScreenWidth
Open up either one first. (I've opened up ScreenHeight.)
Now there are 2 different ways of doing this and depending on what system you have only one of these will work.

Number 1. All you have to do to both of them is change it to decimal and hit ok, then close regedit.

Or

Number 2. Copy the decimal value for the ScreenWidth and click hexadecimal, paste or type it in there and hit ok and do exactly the same thing but to the ScreenHeight.

Now go in-game into Half Life and it should look something like this

Now first off change your resoloution.

Now go to settings go to Video and change your Renderer if you want to. (I usually have OpenGL)

And change your Display mode if you want to.

Well now you should be able to play Half-Life and all your other GoldSrc engine games now, and also you can now go in-game and change the resolution back to your personal setting if it feels a bit Fat or Skinny. :)

(Also If none of that worked and it's still oversized and you can't do anything then just go into your library, then right click on Half Life,Click on Properties,then launch options and add this to your launch options: -h 800 -600)-Credits to 'Ga-fil!' for telling me.

I hope this has helped you fellas, also don't worry anymore, you do not need to worry about wasting your money anymore! Which should relive you.

Also please like this guide,favourite it and share it.