you can still use most third-party apps. All you have to do is be a moderator in a subreddit. for some stupid reason reddit then allows you to still use them because they probably need all help they can get from mods.
Joey as an example still works fine, you nust have to use a older version and block their versions check.
a lot did when the third-party kill happend. i mean, look at the current state of reddit. almost only bots and karma whores posting, but the real core community who really contributed content (bot just reposting stuff but creating it) is being less and less active.