Are you sure? This link shows it as free: https://www.amazon.com/Star-Wars-Knights-Old-Republic/dp/B017UYFNYQ/

Edit: it looks like Amazon Underground was cancelled recently and it doesn't work anymore.

That didn't work. Amazon has some apps labeled "Actually Free" try this link Get Star Wars: Knights of the Old Republic from the Amazon Appstore. Check it out - https://www.amazon.com/dp/B017UYFNYQ/ref=apps_sf_sta

They aren't accepting new apps for it but the old ones that were already on it are still free.

https://www.amazon.com/Star-Wars-Knights-Old-Republic/dp/B017UYFNYQ/ref=sr_1_1?s=mobile-apps&ie=UTF8&qid=1534337748&sr=1-1&keywords=kotor&dpID=81MtqeDWzgL&preST=_SY300_QL70_&dpSrc=srch

I checked this morning and it still appears to be free: https://www.amazon.com/Star-Wars-Knights-Old-Republic/dp/B017UYFNYQ/

Edit: nevermind it looks like Amazon Underground was cancelled recently.

here's a bunch of top quality games on Amazon Underground, better hurry if you want any of em:

these links should all be correct, for the 100% free Amazon Underground versions of the apps. let me know if anything's wrong

• monument valley
• gunbrick
• hitman GO
• lara croft GO
• deus ex GO
• shadow blade
• shadowgun
• monsters ate my birthday cake
• inferno+
• hook (removed from Underground, but available for $1 on Amazon or on Google Play)
• quell
• quell reflect
• quell memento
• the westport independent (removed from Underground)
• puzzle retreat
• type:rider
• almightree
• splice
• dark echo
• punch quest
• badland
• duck tales: remastered (removed from Underground)
• castle of illusion: remastered
• god of light
• all Cut the Rope games + Pudding Monsters
• where's my water
• where's my water 2 (removed from Underground)
• where's my mickey (removed from Underground)
• where's my perry
• toy story: smash it!
• threes
• ghosts of memories
• blown away: secret of the wind
• hitman sniper
• magicka
• goat simulator
• goat simulator: waste of space (removed from Underground)
• goat simulator: goat-z (removed from Underground)
• goat simulator: mmo simulator (removed from Underground)

added from the comments here:

• star wars: KOTOR
• siralim and siralim 2
• games by Halfbrick
• sonic CD and the Sonic dash games
• sorcery and sorcery 2
• knights of pen and paper
• delight games interactive novel collection
• pac man championship DX, along with tournaments and friends

if anyone likes Hidden Object games, there are a bunch from:

• artifex mundi
• big fish
• G5
• Five-BN

you can go here to search for others, make sure the search bar says Underground Apps before you search.

This is amazon.co.uk. For us yanks it's free here.

No problem! If you have a Kindle Fire Tablet, it's actually free on amazon right now or if you run the amazon app store! That's how I'm playing it. https://www.amazon.com/Star-Wars-Knights-Old-Republic/dp/B017UYFNYQ