Brutus, neither the community's forum nor its chatroom is especially active these days (we're a busy bunch y'know!), although the site's main purpose is Sonic game competition. If you observe this
page regularly, you'll notice that Sonic game statistics are still submitted quite frequently to the site by its members, and if you check this
page often, you'll see that some members submit videos and guides too (additionally, some members have YouTube and Twitch channels to which they upload and stream Sonic gameplay). Finally, the site has recently started pulling off Sonic game marathons (one took place last summer, and another this Easter), where the best players in the community work together and stream gameplay here
(typically speedruns) of various Sonic games every afternoon (EST) for a week.
If I were you and wanted to get more involved in the community, I'd start by submitting some game statistics (make certain that you're aware of these
first!) to the site via this
page (and some videos and guides via the other two submission pages if you wish to and have the means to), and if you want to socialize with the site's other members, I recommend continuing forum posting (just ensure that you don't resurrect old topics or spam!), and entering the chatroom if and when you feel like it. Sound good? :P
EDIT: I forgot to mention it beforehand, but every Saturday night (EST) a group of TSC players enter the official SpeedRunsLive IRC channel and race a goal in a Sonic game (before each race season a rota of games is posted in the forum by an admin, listing which games will be raced on which nights, and for a week before each race, the players post votes for a race goal). However, I see that you're not too keen on races anyways, so there's not much point in me giving you any further insight.