What if everything that went wrong on "A Red Letter Day" was not caused by what you thought? What if your teleport ripped a hole in space and time? Now you must travel through time to correct the events and set right your past.

Causality Effect
A Red Letter Day Gone Wrong

  • View media
  • View media
  • View media
  • View media
  • View media
  • View media

Causality Effect has been updated. I have fixed and changed little bugs found in the mod after its release. In other news the mod will be aired in PC Games magizine this month and will be on a DVD disc that comes with your magizine.

Causality Effect
?A Red Letter Day Gone Wrong?

The installer

8 years ago Full Version 4 comments

Download me to install the game

The Video Trailer

9 years ago Movies 0 comments

Check out the trailer with in game footage.

Post comment Comments  (70 - 76 of 76)
alfaalex101 Jun 29 2006 says:

Oh My God! This mod gave me almost the same if not better experiances that I loved from Half Life 2! By far the greatest mod I have played for HL2. The Level design is superb and the ending is very very shocking. I would die to give this mod a 13/10. Just beat it 3 minutes ago and the ending still makes me want to go " Holy **** you ******* BITCH!". The ending all makes sense and leaves an impression on you. Gameplay is nothing short of keeping you on the edge. Want to re-live Half-Life 2 again with a different twist? Download this mod NOW! Even though it is mostly just new levels and no guns it dosent effect the mod at all. I am keeping this mod and going to share it with all my buddies. Oh and the storyline is one of a kind. Thank you so much OnboardError!

+1 vote     reply to comment
ZitaX May 25 2006 says:

Great mod!! I really enyojed the multiple endings! :D

+1 vote     reply to comment
OnboardError Creator
OnboardError May 24 2006 says:

Get the game @ Causalityeffect.irswedish.com

Can I be anymore clear?

+1 vote   reply to comment
GreenTiki Feb 20 2007 says:

I really enjoyed this mod.

Pros: Gameplay is excellent, some of the best firefights i've had in a HL2 mod. I especially enjoyed the antlion part. Storyline was great for a mod that only used the original sounds. The alternate endings were a great idea, and well implemented.

Cons: As far as gameplay goes, none. The level design however had a few spots where the lighting looked very bad, creating some odd shapes on walls and some straight lines, just some things to think about. The brushwork however looked great. Where the wall breaks to get into a room of zombies, I think it would have been nice if it looked a little more realistic. No wall will break in perfectly even boxes.

Overall, I think the rating this mod was given is dead-on, if not a little low. Good job! I look forward to any future mods you create :).

+1 vote     reply to comment
ZitaX May 12 2006 says:

myg02: It looks like its out for download at their website...

+1 vote     reply to comment
fenixphlex Jan 17 2006 says:

sounds good if you can pull it off :thumbs up:

+1 vote     reply to comment
Post a comment

You are not logged in, your comment will be anonymous unless you join the community. Or sign in with your social account:

Half-Life 2
Send Message
Release date
Released 2007
Mod watch
Start tracking
Community Rating



101 votes submitted.

You Say


Ratings closed.

Embed Buttons
Link to Causality Effect by selecting a button and using the embed code provided more...
Causality Effect
Last Update
8 years ago
92 members