A Guide to DLC

DLC - DownLoadable Content. Game content that is released at and after initial release to increase playtime or add additional features.
When it comes to DLC everyone has an opinion. Great gaming evil or amazing extras. Figuring out what DLC is worth while can be a chore but heres a short but sweet guide to help.
Free DLC / Patch
Download! It's free! Sometimes this is just a small addition such as a hard mode or maybe an extra costume, sometimes is new levels or fighters in a brawler but as it's free there is rarely a reason not to download. Many of these are patches that simply add stuff while fixing other stuff or even correcting an error.
Costumes / Skins
AVOID!!! Many games let you download extras that just make certain things look different at a cost. For example, Dead or Alive 5 has over £300 worth of costumes for download. Even at a few pence or a few pound these are never worth the price. If you really want to give your character a new hat, feel free to spend real money on it but just stop at one. These types of DLC are easy to ignore without damaging the gameplay.
New Levels / Extra Missions
Cautiously approach. A running theme in modern gaming is to leave things out of games at release and simply charge extra later. Asura's Wrath was sold with the final chapter seperate, as was a few other games. This kind of thing is very annoying. Sometimes the extra levels are genuinely new and sometimes it's reusing existing content to create a new or remixed level. Always research these first! chances are any major content will get reviewed on both the quality of the new levels and the price. Sometimes a combination of poor workmanship and high price means you can easily skip the offending material, other times it's well made and cheap. If the latter, fork out and enjoy but maybe wait until you've completed the main game first.
Freemium
NOPE! NOPE! NOPE! Even if the game is free, that 59p thing is just a 200x200 pixel .gif and it'll do nothing. If the game won't let you have an item without handing out cash, delete the game. This is mainly a problem with Mobile games on Android and I-Devices so it's not a big problem for proper games but it is coming into a few pc games recently. Always avoid.
Pay-to-Win / One More Go
Another Mobile plague. Avoid! Even if you're one hit away from victory don't pay that few pence/pound for an extra shot. Most games that follow this are freemium and are programmed to screw you over. Again this is appearing in proper games. Never buy into it!
Now You Know?
This guide does need a fixup but hopefully you've learnt a bit. Unfortunately this Wiki does not warn you of dlc in games every time but it should do in the important times. If you've got a game with DLC, remember what you learnt here and use your best judgement. If it's worth your time it's worth your money.
Games with Free DLC
Sonic Lost World (extra levels), Smash Bros 3DSU (via patch), Blue Dragon (Hard Mode), Toki Toki 2 (more levels). *ADD MORE*
Games with worthwhile DLC
Mario Kart 8 (Levels), Pikmin 3 (Missions), Smash Bros 3DSU (Fighters), Hyrule Warriors (Missions and Fighters), New Mario bros U (new game), GTA 4 (new story), Red dead redemption (new story), Witcher III (story DLCs) *add more*
Games with pointless dlc
Dead or Alive 5 (costumes), Halo Reach (costumes), *ADD MORE*