Tekken Tag was a popular follow up, but was mostly focused on just adding back all the characters dropped between 2 & 3. Tekken 3 was the first, where they progressed the timeline 20 years, dropped a bunch of legacy characters, and introduced a new series protagonist. Tekken has had 3 soft reboots in its history. You have to look at the history of Tekken, alongside the history of fighting games. Long time fans loved it and it also brought a ton of new people in. It succeeded because the devs focused pretty much exclusively on gameplay. A lot of shortcuts were taken when it comes to the visuals of the game (characters have less closeup details than in Tag 2), but the game still looks pretty damn good, can run on toasters and has excellent gameplay. Tekken 7 had a comparatively low production budget and was basically a last attempt to revitalize the series.

Tekken 7 was initially released exclusively in arcades and was later completely remade, relaunching with a new engine in arcades and on consoles. Tag 2 basically almost killed the series due to massively underperforming sales. Tekken Revolution, a F2P game was released and failed, got shut down. Online was still pretty crap, even for fighting games at the time. It had a ton of content, but unlike older Tekken games, gameplay issues compounded at higher levels. Tekken Tag 2 was released with relatively weak marketing and wasn't exactly beloved by longtime Tekken fans due to balance issues. Tekken 6 was proper big budget and with a major story mode, but had major issues regarding online play. Then they release an enhanced edition of Tekken 5 exclusively on PSP for some reason, which did come to the PS3 a while later. Tekken 5 then established the feel of 'modern' Tekken games and sold pretty well. Tekken Tag 1 and 4 didn't have the sales numbers of 3 because Tag 1 was released exclusivity on a console with at the time a low user base and 4 burned a lot of people due to how different it was from 3/Tag 1. Tekken 3 was massive because it was a great looking game with great gameplay on a console with a huge user base at the time.

Copies of tekken 7 sold on xboxone