Mobile games you can play in your browser without ads via YouTube: https://www.youtube.com/playables
Please let me know if you add any to IGDB, the vast majority currently aren't on there.

Not on IGDB (company given if the name is particularly generic):
8 Ball Billiards Classic (Famobi)
Angry Birds Showdown
Basketball FRVR
Block Drop (GameSnacks)
Brain Out (Focus Apps)
Bubble Pop Star
Cannon Balls 3D (Famobi)
Cards of the Undead
Carrom Clash (GameSnacks)
Chess Classic (Famobi)
Collect Em All! (Voodoo)
Color Burst 3D (VAEV inc)
Color Match (SuperSonic / Carawell)
Color Page ASMR
Color Pixel Art (Famobi)
Crazy Caves (Famobi)
Cube Master 3D
Cube Tower (GameSnacks)
Daily Solitaire (Arkadium)
Draw Climber (Voodoo)
Element Blocks (Famobi)
Emoji Puzzle (SuperSonic / Fun Velikan)
Find Out (Focus Apps)
FreeCell Solitaire (Arkadium)
Fullspeed Racing (GameSnacks)
Gin Rummy (GameSnacks)
Gold Mahjong FRVR
Idle Restaurants (GameSnacks)
Jewels Planet (Teskin Games)
Knock'em All (Voodoo)
Ludo Karts
Makeup Kit - Color Mixing
Merge Heroes (GameSnacks)
Merge Pirates (GameSnacks)
Moving Co. (GameSnacks)
My Space Pet (GameSnacks)
Northern Heights (GameSnacks)
Onet Connect Classic (Famobi)
Pirate Pop (GameSnacks)
Pocket Battle Royale (GameSnacks)
Pocket Champions (GameSnacks)
Rainy Boba Cafe (Google)
Retro Drift (GameSnacks)
Scooter Xtreme
Slice It All! (Voodoo)
Stack Bounce (GameSnacks)
State.io (Casual Azur)
Super Goal (Gamegou)
Tile Master (Higgs Studio)
Today's Hurdle (Arkadium)
Turbo Stars
Words of Wonders (Famobi)
Words of Wonders: Guru