Devil May Cry is really a bizarre series. It started with the first game which practically invented its own genre "Spectacle fighters". Then came the second game which was outsourced to another developer for reasons that will forever be left unknown. It wasn't a horrible game...not that horrible anyway.
DMC3 was THE redemption on Capcom's part. They gave us a game which aged incredibly well in the gameplay department. It was so good that fans were ultimately let down by its lackluster sequal DMC4. Capcom had decided to cut corners like no tommorow and we were left with a game that repeats itself with absurd level design. Combat was still god but it felt unfocused with two characters with limited movesets and weapons. It is almost tragic to see a company that is this confused and clumsy with its own IP's especialy such an iconic one. It is like seeing a jumbo jet being used as a school bus.
Haven't played the reboot so can't comment on that. Doubt I will ever either.
Hero in a half shell:
Command and Conquer.
It began as an innovative RTS series with awesome campaign scenarios and mesmerizing camp cutscenes, and has ended up a multiplayer only Free2Play cash cow.
C&C for me as well.
Also, Halo 4 multiplayer. 343i are despicable and have spat in the faces of anyone with a shred of respect for competitive multiplayer and any member of the loyal Halo fanbase. They did wonders with the singleplayer, it was glorious, but as I've said many times before, multiplayer and disc 2 as a whole is an insult. I don't even view it as a mistake, it's a pure insult to me as a videogame consumer and a Halo fan.
Oh, and Splinter Cell Conviction, Rainbow Six Vegas and Ghost Recon Future Soldier. Now, the first 2 of those games are still good games in their own right, but they're not torchbearers for the games they're successors of. They do, however, top of the list for derailed series where the pub/devs have kicked dirt in the eyes of long-term fans. Take Ghost Recon, and play it alongside Future Soldier. I'm not even sure why they have the same name, to be honest. They're totally fucking different genres, they give nothing that can be viewed in the same light and they appeal to a completely opposite spectrum of the market. Ubisoft can go fuck themselves over Ghost Recon Future Solider.
I don't like plainly insulting someone's career, work, creation, hobby, etc., but GR: Future Soldier, Halo 4's multiplayer and C&C4 are fucking bad. They're really, really bad and a barefaced insult to genre consumers and their respectful dedicated fanbases. I think I'd rather be spat in the face and told to fuck off by the developers and publishers of those game, than baited into buying them on the broad mass-appeal marketing as I was.
PR/Marketing: "Our game's like the last one, but better! If you liked it before then you'll love it now, and we're thinking about you throughout development - if you've never played it before, we've made it easier for you to get into our game as well! Everybody's gonna' love it!"
BULLSHIT. That's an impossible feat to do to a titular series that stands tall within its genre. I only see a worse if-not ruined series because of a desire to sell more copies via broader appeal, as opposed to selling copies for being the best in a genre. It's especially clear in those games I've listed above.
Resident Evil franchise.
Despite the fact that most people like RE4 for me it stopped being RE at that point.
I LOVE Resident Evil 4, but I agree. Resident Evil before and after 4 are incredibly different, the genre has changed completely. Resident Evil 4 wasn't scary, but it had its moments where you could see attempts at being scary. Resident Evil 5 was more of an action game than 4 and that takes a lot. I haven't even bothered with 6 and I doubt I'll ever will.
Besides that I can't really think of anything.
Carmageddon, I love 1, 2 and it's ps1 version to bits but damn did TDR2000, GBA and N64 port suck. Oh well, the last 3 weren't even developed by stainless so I have all rights to declare them not part of the story.
Assassin's Creed for me as well. I liked the first one, but the other ones forgotten about halfway that they're supposed to be about, I dunno, assassinations and assassin stuff. Not mashed gameplay styles together.
Sad, sad thing indeed.
Devil May Cry.
Now I like me some change. But to take out everything that made the originals 1, 3 and 4 so great, in favor of a reboot that panders to casuals with easy and slow gameplay and story lovers for a story that is mediocre to the core...
Ah screw it, at least Shin Megami Tensai has never failed whatsoever.
Silent Hill. I am one of those people who get very nit picky when companies make a sequel to a game and get the foundation for the story totally wrong. When Homecoming came out I was so excited to play another installment to my favorite survival horror series. When Pyramid Head came out I was like "He doesn't belong here.", and the fact that The Order were attacking you didn't make any sense to me seeing as how they were non-violent. I know the background to SH pretty well and things like that ruined it for me. Also the fact that it wasn't actually scary, just startling.
Ace Combat. AC4, AC5 and AC0 were the best in the series, all on ps2. Then came AC6 as an Xbox exclusive but it was still decent and then Ace Combat Assault horizon... It was an abomination, it ruined every single fucking thing that was good about this series, it gave us bland and generic protagonist instead of just naming the pilot and leaving it like that, it added stupid QTEs that don't even fucking matter, removed the fictional universe of Belka, Yuktobania, Osea... and replaced it with modern world, taking down enemy aces was bullshit with that awful mechanic that forced you in stupid "take down mode" or whatever, story was shit with cliches such as "America FUCK YEAH!" and "Fuck the Russians!"... This was meant to take series in different and "better" direction when it didn't even need one, for purpose of introducing it to the wider audience. It got branded in reviews "Call of Duty IN THE AIR!" as a compliment... oh, how right they were...
Armored Core - From Software original Hardcore game. Armored Core 3 was the best in the series, but other parts like Nexus, Silent Line, Nine Breakers and of course Last raven were also awesome. This was all nice and pretty until Armored Core 4 and For answer came to ps3 and box 360. It was different yeah, but it wasn't bad, controls were different and this was a deal breaker for most fans. See Armored Core was all about customizing your AC and all of them played differently, levels were tightly designed and each boss required different approach, the games were balls-to-the-walls hard (it is From Software we are talking about) and it really did appeal to niche audience, and when AC4 came it was all simplified: Bosses were completely forgettable, levels were huge and provided more room to move throwing out strategizing movement through the window, most AC setups acted the same and it was too fucking easy compared to say... AC: Last Raven. But all in all it was still decent enough I guess, where the series actually fell apart and went to hell was in Armored Core V, which was abysmal: it was even easier than the 4, ACs were tiny, it was painfully short and they added Fucking multiplayer to the game which was shoehorned so painfully bad that managed to deforme the whole game.
Devil May Cry... You know I opened some old wounds now that I won't even bother with this one as it was recent enough for most of you to know what the big deal is.
And there we go! 3 of my fav games that went to shit, sorry for the wall of text.
Most of the ones I can think of have already been mentioned, and I've said this in another thread, but my choice would go to the Rainbow Six series.
How these games have changed... I mean, the first R6 was a hardcore tactical simulator, where a lot of the game was spent in the mission planning phase, equipping your soldiers and planning the mission. Rogue Spear only improved on this, and the sequel was even better than the first game! Raven Shield was pretty much Rogue Spear with better graphics, and that wasn't bad at all.
And then it all went to hell... the numerous spin-off's, the 3rd person perspective, the loss of the mission planning phase, the dumbed-down enemies... I mean, you can see how bad it got when R6: Vegas was hailed as a return of the series to good quality territory... and it still is a pale shadow of the first games! It's no longer a tactical shooter, now it's just... a shooter. Where you do hand signals and rappel off buildings. Yay..?
And the very messy development of the next game in the series, including staff getting shafted or quitting and the game getting pushed back "to the next generation of consoles" doesn't give me much hope, either.
Resident Evil 6 and Soul Calibur 5 were massively disappointing to me. Not buying another game in either of these series unless I hear many rave reviews.