How not to starve:
Where to eat

Aahar/Tikka Complex

Location

This is a small complex located about 1 km inside the campus, opposite the Clocktower. It has the following shops:

• (New) Tikka : An extremely cheap restaurant with a variety of options. Hygiene has been mentioned as a potential issue.

• Dominos : Yesh, an actual dominos. Similar prices to outside campus dominos, but taste varies.

• KFC : Same case as dominos, but pretty good for chicken stuff from what I've heard (As it should be)

• WOW Momo/China/Chicken : Pretty good but also Costly.

• Keventers : Milkshake/Ice cream shop. Costly, haven't tried, but heard it's good

• Yellow straw : Healthy for your stomach, draining for your wallet

• Tea Junction : Decent beverages from what I have head, but haven't tried it.

• Calcutta 64 : Full service restaurant, Costly, but decently tasty.

CCD/Heritage Spot

Location

This is a collection of buildings and shops in the middle of campus, on the path from Gymkhana to Main Building. The following shops are there:

• Cafe Coffee Day : The eponym (your word of the day!) of this location, about half price as outside campus CCD, but just as tasty. Still costly though.

• Heritage : A full service restaurant, geared toward northern cuisines, and not too costly. Entrance is inside the complex.

• Mio Amore : The campus cake shop. Decent prices, but cakes will get over by late evening. 

• Banana Leaf : A full service restaurant, this time geared towards south indian cuisine. If you're a southie, it's a coin toss on whether you'll like it. Slightly costly.

• SmartPind : The campus northie/punjabi cuisine restaurant. Decently priced, and the food is good.

• Iosys : A small shop with decent south indian servings, predominantly dosas & fast food. Mid prices.

• Amul Ice Cream centre : As the name suggests. Not too costly if you buy multiple scoops.

• Waterballs :  Pani Puri and other related chaat items. Not bad, decent price. 

• Momo Mania : Haven't tried them, but for momos, price is on upper end.

• Some coffee thingie : Decent chai/coffee, but others are costly

Nalanda Spot

Located mostly near, well, the subway side. Ye shocker!

• Subway : Classic ol' subway. High Costs, Decently Healthy, Tasty. Menu changes often though, imo.

• MFS Canteen : Relatively cheap, small menu. Clueless about hygiene, but the food is always hot. Often Crowded. Best Aloo Paratha of my life though.

• Nescy : "Fastest Food." Most of the snacks is premade, and given after being heated. Cheapest.

• Roosters : The KFC of the campus before KFC came. Be careful with non-veg. Pretty good fastfood (McD/KFC kind of fast food).  Medium-Costly in Price.

One-Off/Single Restaurants

PFC (Pan Food Centre) - Location
Near the PAN loop, i.e. near the side road to LBS hall.
On the costlier end, but the food matches in taste & quality (most times).
Full service with most cuisines available (chinese, north & south indian, Continental)
If you convince your seniors for giving a treat here => go into negotiating, you're a natural.

Dreamlands & Sahara - Location
Technically two restaurants, right next to each other.
Sahara - Mid-Cheap Cost. Other collection of shops (Fast foods, Snacks) are also nearby. Food is good, Biryani is considered great.
Dreamlands - Big Variety, though more Bengali-influenced/type of restaurant. Prices might be a bit too much for the food, but do check yourself.

SuperDuper (SupDup) - Location
Predominantly visited by Seniors, but no limits for you guys visiting too.
Costly, but wraps & similar fast food is known to be good. Thali and such might not be as great.

Veggies/Desi Tadka - Location
Was a pure veg restaurant, but might have changed now. The food was decent/good, and the ambience was great. Costly though, especially unexpected stuff.
Technically this might also come under a Heritage Spot Restaurant, but it's far enough in my opinion to be considered different.

Food City - Location
So, this one's a secret for you to find out on your own.

Agri Canteen 

This is an old multipurpose hall that has been turned into a canteen in the Dept of Agriculture & Food Sciences. Justifiably so, given that the dept alone is bigger than IIT Delhi in terms of area. The food here is genuinely mid - like perfectly average quality for IITKGP food, at the perfectly average price.

Nescy Shops

This is technically a collection/franchise of shops: basically surmised by its name: Nescafe shop. It's there in most halls, and also certain common places like Nalanda & Main Building. It's menu is simple and is mostly a variation of maggi, cold & hot coffee/tea, Puffs and other Indian fast food.

TechM Shops

At the backside of Tech market,  lies a collection of restaurants, hyperspecialized to certain cuisines. There are also a couple of eateries within TechM itself. I have honestly had the best momos here; and most food here is good and really cheap. Hygiene is something to watch out for: I basically only ate stuff which were really hot.

Entrance Shops

These are a collection of eateries just outside the main (puri) gate, i.e. literally walkable (100-300 m). They are often considered much better than many restaurants in campus, but are also costly (With a couple exceptions). You should also be able to order from these restaurants on delivery apps.
That being said, the shops here are for you to find, I can't tell everythinggg.

[Lastly, this is not exhaustive, I have skipped some for you to discover, and missed some that I haven't discovered myself]

Night Canteens

These are canteens in halls, separate from the actual mess, and it's timings are often around 7PM-2AM (variable). All are located within their halls. So if you want to find their location, just search up the halls (the names I have given)

Open to all (Boys & Girls)

HJB : Opposite Gymkhana, this is the most common night canteen visited. Decent fast food (Wraps & such), Decent South Indian, Okay biryani & curries. Many like the drinks (juices & such) here. Not too costly, but not cheap either.

VS : One of the cheapest canteens in campus, its food is up-to-taste. Milkshakes are good though.

JCB : Just behind HJB, this is like its forgotten brother. Prices are a bit cheaper; and the food was about as good in m opinion. Less options though. 

BCR Nescy : Technically not a night canteen, it's a nescy shop in BC Roy hall of residence (Different from BC Roy Hospital), so has lower options (Buns, Puffs, Maggi, Cold & hot coffee & tea). It's open to both however, & is the closest eatery to Library/Maggu Room in Main Building at night (after Main Building Nescy has closed).

Boys Specific

All boys hostel have one, so anything not in the above common night-canteens are open to boys.

LBS : Has a variety of dishes, mostly fastfood (indian) and stuff like maggi. Heard rumors about hygiene here too, so be careful when you try. Cost is average, and taste is decent. Recently opened, so new dishes are being added every few weeks.

From the opinions of my friends, each Canteen/hall has dishes its good at, and other dishes... we don't speak about. As such, there's no real best canteen, but mostly personal preferences. MMM & LLR night canteens are relatively close-by, but RP is considered one of the faster service ones. Most of the night canteens are known for their non-veg items. My recommendation: try your fav food or two in each canteen before deciding what's your go to.

Girls Specific

SNVH : They offer a variety of dishes ranging from paratha and Maggi to fried rice and pavbhaji. They also have packaged foods like chips and such, a popcorn machine, and some bakery items. Food is decent and prices are ok.

MT : No night canteen here but a small Nescafe. You can get good coffee and Maggi. There's a snacks shop next to it, but that opens only during the day. Prices are ok.

Ordering Online

Zomato/Swiggy will single-handedly increase the number of available restaurants by two or threefold, and I was discovering new restaurants 1 year in, so definitely explore this.

Most restaurants within 5-10km of campus will be available there, with exceptions. For restaurants inside, average time of delivery is 15-30 min, while those outside take 30-60 mins. Do note that the food is more costlier than ordering in-person, for obvious reasons.