With part 1 here, let's jump straight into part 2... (stick around for the end for my favorite sense to mess around with).

TOUCH

This is where D&D and it's adjacent games have something ahead of most rules-lite games; miniatures. Seeing a miniature is always fascinating, but the number of times I've seen people move miniatures like meeples on a game board with absolute joy is uncountable. There's an unspoken joy about counting squares and feeling the tactile movement of the characters as you barely reach the enemy. This is why Warhammer is such a popular game - the combination of visual and touch (and many dice).

The second part of touch is the dice. People love the feeling of many dice in their hands. This is why the 8d6 in fireball is "acceptable". It's worth counting the math. People like the click clacks, and providing click clacks for the newer players especially who are just joining in the hobby is essential. Unlocking anyone's inner goblin is a surefire way to get them into the TTRPG space.

The last thing I want to mention are textures. I personally don't play with this much, but having a piece of wood to feel as the tavern's table, or a piece of silk cloth for the nobleman's dining table cloth has to be something that improves immersion. This would be bordering on the territory of the less prioritised senses... like smell and taste.

Smell & Taste

Now, these senses are on my low priority list, but when I get a GM who has these down, it is both impressive and super immersive. Imagine being in a tavern (I know, this is just the easiest location for me to describe), and you smell the ale and bread. I've seen some candles and it puts in that last 5% to 10% of immersion for me. 

Taste on the other hand is specific for meals and drinks - a good meal or drink fits, but sometimes even when I as a GM am eating an apple as the BBEG eats an apple, it helps give just a little bit more character to NPCs. This, like smell however, puts in the final 5% of immersion.

Both taste and smell are not as actively used as even touch, let alone hearing and sight. The best taste and smell will not trump a well crafted audio-visual environment. But it is a nice cherry on top when you can.

Honorary senses

Gravity or sense of balance - if you've ever played Dread, try playing it while standing on one leg.

Thermoception - I don't know about you, but when the room gets too hot, people get MAD. Keep the room cool for calm and collected game experience. Maybe increase the temp a little and see how people react when fighting a frustrating boss. This is not GM advice. HAHA

The 6th Sense

Chronoception. Time. A sense of time. Adding a timer/minute glass to my tables has been an absolute game changer. Just adding the minute timer, even if I don't stick to it is enough to get people to lock in and make a decision. There's something primal about a timer that makes people act quickly and rashly. This often makes for great drama and simulates intensity. 

A less urgent way to create urgency is by using clocks. Explaining clocks is an article on it's own, and that link should help ya. Using clocks feels revolutionary but in practice, it's just a hit point bar but with less of an incentive to hit it, and more of call to solve it. This is a classic way many GMs I know create some alternative to the bog standard combat that 5e has. 

Conclusion

If I were to logically work through this again from the start, I would begin with curating or sourcing for good playlists. Just enough playlists for your next session - over the years of running games, you'll create a library so vast, you'll have the write playlist for everything.

Then work on character, location, and object art. Pull from the internet, draw it out yourself. In tandem, I'd work with descriptive skills and vocabulary to help immerse the players in the vision of the characters. This will allow you to not be married to how the art looks, and improve your originality when it comes to making new characters.

Then I'd actually throw in investing in a good clock or minute hand. Sure, your phone timer will work for now, but personally I like the mix of using an automated timer on Foundry VTT (my VTT of choice) and a minute clock.

Every other sense to me is icing on the cake. I have tonnes of dice and miniatures. Go get your candles and tavern breads. 

That's all folks, and don't forget - who's awesome? You're awesome.