Well, you don't really "beat" fighting and puzzle games, do you? Unless there's a story mode and those are usually very short. I consider Tekken completed when I unlocked all characters and filled Theater Mode. Now you don't unlock much and cosmetics grind never ends, so it's just getting all endings.
But yeah I used to have a HUGE problem of restartitis, I have countless RPGs started and dropped because I want to recreate a character... or find out I missed tons of stuff before. Worst example is Bioware games, I finished KOTOR dilogy and Mass Effect trilogy multiple times, but Baldur's Gate and Icewind Dale is party creation simulators. Fallout and Dragon Age are modding toolkits with games being attached to them. So...
I got out of the cycle of endless restarts by actually picking some shorter games to just get to the end, selected more manageable games to 100%, and finally, focused on more linear RPGs without open world distracting you so much.
Like, I have a save in FF1 right before final dungeon from years ago... and FF13 in the last 20% of the game or so, but I got all tails and summons in FF4 and finished it properly, then went through the PAINFUL minigames in FFX, and on track to one-shot the last bosses like I Rikku mugged Seymour. xD Note that I am deliberately choosing the MOST linear RPGs because you get lost in more open games forever.
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I actually went back and finished first, original Assassin's Creed, so now I have Ezio games and Origins done 100%, same with first five Tomb Raiders and Rise... Where I need to pick up my 87% save from TR2013.
Problem with these games is you get burned out way before you can finish them, I love when you can do the post-game completion for treasure search and collectathons, most older RPGs forcing you to go back before final fight and spend hours grinding for useless items when you could have just finished the story is bad game design, no two ways around that... But thanks to post-game, Rise of the Tomb Raider is one of very few modern games I have a 100% save on, it didn't overstay its welcome. AC Origins is also well paced.
So to avoid burnout, I take breaks and switch to short arcade games. Apart from having a Retroarch setup on Steam with RetroAchievements and all, I also got a PS3 with custom firmware and some arcade ports installed, it's a really neat console where you can emulate three others natively and play Crazy Taxi or Daytona USA on breaks... or get a few rounds in Tekken TAG HD.
What this all boils down to is that to avoid being burning out between endless fighters and modern-ish games that reward you for exploring endlessly, and actually enjoy them without a feeling of "I haven't actually finished a game in years", I just go through something like Golden Axe, Contra, Metal Slug, or Final Fight, you need like what, 40 minutes for each? That's less than one Blitzball league and I went through like three or four to get ONE weapon.
And sometimes I got insane and try to 100% achievements in Civilization 5 and 6, a game series that I literally never finished a game on. There are saves that help with that. It's crazy but fun!
But overall, I just learned to stop worrying and enjoy games I can't do perfectly, and I found out letting games play even with something missed is far more enjoyable than restarting all the time and then being so OP at the end, the grind had no point to it.
