#18 - Ys: Oath in Felghana (90% Kudos to Player2 for guessing this)

I feel like I've said a few times during this thread that I've been surprised by how much I've loved a game the first time I play it, and OiF is definitely one of those games.  Bought in a PSN sale to get me ready for the upcoming Ys: Memories of Celceta, it actually turned out to be one of the best JRPG's I've played in years and a huge amount of fun.

Part Zelda; part 2D platformer; part hack 'n' slash and part JRPG, Oath is definitely the weirdest of the Ys games I've played and yet it works so bloody well.  You're always doing something entertaining - exploring dungeons; fighting bosses or exploring towns and talking to strange villagers, it's all in here.

Throw in a fantastic soundtrack and some genuinely mind-blowing boss battles (that also pose a massive challenge, too) and you've got one of the most enjoyable games I've played in years.  Slight mis-steps were made with the story and it's not the prettiest game I've ever played, but exploring the land of Felghana with Adol and Dogi was an adventure I was very happy to be taking.

Clue for my #17 - a game from 2007 which was recently updated with a horde mode. Sold as part of a box set; as an individual download and is now free-to-play.

Clue for my #16 - final game in a sixth-gen trilogy. Contained levels that involved having shootouts in a castle in Scotland in the 1920's; battling zombies & ghosts in a haunted mansion in the 1990's and a train chase in the swinging 60's, against Blofeld... or thereabouts.

#19 - WipEout 2048 (Kudos to no-one for guessing this)

Everything a WipEout game should be.  After 15 years, I suppose you'd hope that Studio Liverpool would be masters of the futuristic racer, and they most definitely are.

Although missing one integral feature (racebox), everything else is more than fantastic enough to make up for it.  The graphics are gorgeous; the soundtrack is great; the gameplay is a refinement of everything since Pure onwards; the online multi-player is incentivized greatly to keep you coming back for more; the campaign is greatly balanced and the zone mode is the best ever; fantastic tracks and beautiful locations.  Just everything you'd want it to be.

A fitting swansong for one of my favourite gaming studios of all time.

#16

TimeSplitters: Future Perfect.

*nod*

Totally hope those rumours of a new one turn out to be true.

Anyway, I'll update my hint for #16 since nobody got it.

#16 - Edge...Undo.

I noticed my mistake.  I left out some words in the hint.   Rewrote the hint.  The eight bosses have a dark version in the specific game I'm talking about, where all these bosses were in the previous game.  Not an RPG though.

Hints

17.  You fight dark versions of eight bosses that were in the previous game. 

16.  The main character is the last boss when playing in a different mode as the games three supporting characters.

18. Super Smash Bros (29 last year) first impression 8.5, replay 10, technical 7.5

Pros: It launched the Smash Bros franchise, with its focus on fast-paced fighting action that, for once, did not revolve around endless combos and instead focused on spatial maneuvers, platforming, and singular strikes. Chuck in 12 iconic Nintendo characters, and you have an instant classic.

Cons: Rather paltry content-wise compared to the games that came later.

17 was the only game in its franchise to feature a protagonist who was not of royal lineage (the game's direct sequel, higher up on my list, *seemed* that way, until it turned out that she was the actual Empress and the real one was her younger sister). He was, instead, a mercenary.