DRAMAtical Murder

They are both based on a BL game that involves fighting. They were also made by the same company. 

Both are based on BL games created by Nitro+Chiral and involve a male protagonist being placed into life-or-death situations. 

Both are non-yaoi adaptions of yaoi games from the same company, as someone somewhere thought that was a good idea. Being from the same company, they both have several things similiar. Some sort of slightly dystopia world, some sort of game. Akira and Aoba, the main characters of these two anime, more or less have the same exact backstory. A few of the characters are also similiar. And both of these shows have absolutely terrible animation.  

Both are based on BL games of the same company (Nitro+Chiral, the BL-branch of Nitroplus). All of them share the genres of Action and Sci-Fi. But in DRAMAtical Murder you won't find any Shounen Ai or Yaoi part while in Togainu you can find Shounen Ai. Moreover the two animes are worth playing games even if the animation don't seem to be appealing... 

Both are produced by Nitro+Chiral so that should make it obvious that there would be many similarities. Both are anime based on a visual novel of the same name and both have shounen-ai content although the games have a lot more of this as well as more violence and blood as a lot of this was censored in the anime adaption (especially in Togainu No Chi's case). They both have similar themes and even the characters are similar in some ways exp. the relationship between Akira (Protag) and Keisuke (Childhood friend character) reminds me of how Clear behaves with Aoba. Also, if you liked the overall game-theme DRAMAtical Murder provided, Togainu No Chi also has this in a sense, the protag is involved in a street game called Bl@ster and without giving any spoilers the entire series is set in a game of life and death in itself. Another thing to mention is both are set in similar yet opposite settings, both are set in a cityscape type setting, the main difference is you can think of Togainu No Chi as a more apocalyptic or dark version of the futuristic setting you see in DMMd. read more 

Both are edgy bl series based around visual novels and also lots of action in it as well too. 

they're games made by the same company made into an animated version that is less sexual 

-They have power to save the world -deep memories -deep song - Blue,Red main character :D 

- Similar Color - Hot and cute Guys xD - looks like a game 

Both are trippy stories with lots of weird shit happening and also really nice visuals and art too look at too. 

If you enjoy anime series based on themes such as self-acceptance, you'll enjoy both Dramatical Murder and Persona 4. 

These two shows are very identical; they both take place in games, interesting characters, and more. Both have very interesting plots, filled with action, comedy here and there, mystery, and more. If you enjoyed Sword Art Online, you most likely would enjoy DRAMAtical Murder as well. DRAMAtical Murder would be one of my favorites, I highly recommend it. 

They both have a cast of attractive guys, with action although in Free! it's swimming and in DRAMAtical it's fighting a game called "Rhyme". They both have a good deal of focus on male friendship. Both have casts that are almost completely made up of guys with one main character, ( Haru for Free! and Aoba in DRAMAtical). Both Haru and Aoba have something that sets them apart somewhat from their friends, but the bonds are still very strong .They may have different topics and themes, but many aspects of the two are the same.