$0.25 NL - Holdem - 9 players

MP+2: $35.59
CO: $29.80
BTN: $30.72
SB: $44.95
BB: $30.14
UTG: $27.07
Hero (UTG+1): $25.00
MP: $22.70
MP+1: $8.20

SB posts SB $0.10, BB posts BB $0.25

Pre Flop: (pot: $0.35) Hero has 6 6

UTG raises to $0.55, Hero calls $0.55, MP raises to $2.55, fold, fold, fold, fold, fold, BB calls $2.30, UTG calls $2.00, Hero calls $2.00

Flop: ($10.30, 4 players) 8 8 6
BB checks, UTG checks, Hero checks, MP checks

Turn: ($10.30, 4 players) 9
BB checks, UTG bets $4.75, Hero calls $4.75, fold, fold

River: ($19.80, 2 players) Q
UTG bets $10.50, Hero calls $10.50

6 hands - no meaningful stats or reads

Preflop
Normally I don't call a 3Bet with small/middle PP´s.
But in this case, with two calls and a good relativ position to the aggressor, I thought it can be a good spot with enough implieds if I hit my set.

Flop
So my maintargets are the hopefully strong flatcallrange from UTG and the strong 3Bet Range from MP.
Possible UTG Flatcallrange:
AJs, AQo/s, KQs
88-JJ, (QQ)
4Bet Pre: AK, AA, KK, (QQ) in this spot I think.
The MP 3Bet Range can be a little bit wider imo.

All checked, so I think MP only has HighCards.
JJ+ he will bet I think against 3 Villains.

Turn
UTG Bets nearly 1/2 Pot. Now he is not scared for a Overpair from MP and kann bet: 88-JJ (QQ)
Also he can steal the Pot with a FD´s + HC´s: (AKc), AQc, KQc
Don't now he can have here a pure bluff against 3 Villains in a 3Bet Pot?

If I shove he mucks his FD´s and Bluffs.
Also I´m dead against 88, 99
He calls maybe: TT, JJ, QQ

River
2nd time nearly 1/2 pot.
But what he is betting here 42BB, what I can beat If I raise All In and he calls?

Maybe he bets: 88, 99, QQ, AQs, KQs, (AKs for bluff??)
Maybe he checks: TT, JJ

I thought the only hands that I beat and call my shove are: AQs, KQs
Other hands I beat go into the muck imo.
The rest are better hands and I loose the whole stack.

To tight thinking???

I think you're right in saying there aren't many hands you beat that would call here. Would he have bet bigger (>0.5 pot) on the river with a better hand for value after you called the turn? Hard to say without knowing much about villain.

I think if a club comes on the river you shove, as there are more hands that'd call and only 4 combos that beat you (8c8s, 9s9d, 9h9d, 9s9h), or 3 if the river is 8c.