Yet another train [Level 3+] [Hints added] [OVER] [Solutions posted]

Have you had enough of trains today? Of course not! More trains!

There's no special theme to this one. It's just a train full of games brought to you by Gaben Claus. All of the giveaways are old bundle leftovers from 2012 and are open to level 3 and up. There are five hidden non-bundle giveaways at the end of the train. They're not AAA or anything, but they seem to be well liked by the Steam community.

Without further ado, let's choo-choo!

Like I promised, it's Wednesday, so it's hint time!

The biggest hint I could possibly give is to link you to the zelgh magic guide to basic sg puzzling. Not only is it great for solving puzzles, but it's a great guide for creating them as well. There's lots of cool ideas you can get from it if you're thinking of making your own puzzles. It's definitely worth a bookmark.

That guide alone should be enough to find several of the hidden giveaways.
Hints for the second hidden giveaway: it's not a link and you need a time machine.
Hint for the fourth hidden giveaway: remember where you found the second giveaway.

Solution for the hidden giveaways:

1. On the description for the last giveaway in the normal train, you had to look at the source for the hidden link. If you're using Firefox, you can select the text, right click, and click "View Selectoin Source". To do this on Chrome, you need to download Chrome extension source viewer. Of course, you can still do it the old fashioned way, too.
2. Like the last one, you had to view the source. You will see <a href="Nihilumbra">. A lot of people thought this was a link and clicked it, which just refeshes the view of the source code (at least it does for Firefox). It wasn't a link. You had to look through my old giveaways to find my Nihilumbra giveaway from three months ago. I made a comment there with the code for the second giveaway.
3. The five letter code was hidden in the top of the image. You had to open the image in some kind of image editing software like Photoshop or Gimp and play with the brightness and contrast until the code for the third giveaway became visible.
4. You probably noticed that when you hover over my dog pics, you found a letter. People rightly guessed that it was a five letter code for the fourth giveaway but few people found all five. I put those letters on each dog pic you found up to that point and they were in order: the last normal train giveaway, hidden 1, hidden 2, Nihilumbra (I think this is the one people missed), and hidden 3.
5. You had to save the pic to your hard drive and then open it in a text editor. At the bottom you would find "dRJ8r".

This was my first puzzle train. I thought I made it really simple because I used tricks I've seen many times in puzzles before. I was very surprised at how few made it to the end. I guess it's hard to tell how difficult your puzzle really is when you're the one making it. The biggest bottleneck was the Nihilumbra thing. I never thought that people would think it was a link and that confused a lot of people, so I'm sorry about that. I honestly thought the last puzzle would be the hardest since I rarely see puzzles use that method.

I want to thank zelghadis for the guide to puzzles. I've already sung my praises of it, but it really was essential to making and solving this puzzle. Also, thank you to everyone who participated, commented, bumped, and put up with my confusing puzzles. It was a blast!