ampullae:

What order?

I highly recommend release order:

• Metal Gear
• Metal Gear 2: Solid Snake
• Metal Gear Solid
• Metal Gear Solid 2: Sons of Liberty
• Metal Gear Solid 3: Snake Eater
• Metal Gear Solid 4: Guns of the Patriots
• Metal Gear Solid: Peace Walker
• Metal Gear Solid V: Ground Zeroes & The Phantom Pain

If you are an absolute stickler for chronological order, here:

• Metal Gear Solid 3: Snake Eater
• Metal Gear Solid: Peace Walker
• Metal Gear Solid V: Ground Zeroes & The Phantom Pain
• Metal Gear
• Metal Gear 2: Solid Snake
• Metal Gear Solid
• Metal Gear Solid 2: Sons of Liberty
• Metal Gear Solid 4: Guns of the Patriots

Are Metal Gear 1 & 2 necessary?

You can read a plot summary of Metal Gear. But Metal Gear 2 has a lot of plot points and characters that return in the next game. I’d say don’t skip unless you just really really can’t get into old 2D games.

What about Portable Ops?

It’s not really canon.

Original Metal Gear Solid or Twin Snakes Remake?

I’m always gonna vouch for the original, unless you absolutely need more polygons.  It’s more or less the same– just directed like a fanboy’s version of The Matrix.

Playing options:

There’s two collections that have a majority of the games:

• Metal Gear Solid HD Collection – MG1, MG2, MGS2, MGS3, MGS: PW
• Metal Gear Solid Legacy Collection – MG1, MG2, MGS2, MGS3, MGS4, MGS: PW (plus a download code for MGS1 if bought new)

I really recommend playing if you can because they have some unique and enjoyable segments. If that’s not an option, I’d vote for a movie that features some gameplay or a let’s play over a cutscene compilation.

Anything else?

Yes, Metal Gear Rising is the best spin-off ever. It’s hack-n-slash rather than stealth, but it has the typical off-the-rails plot and endearing characters. It takes place after MGS4.