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_{This is a third puzzle from the Monoalphabetic Equation series, you can check out the previous one here: #1, #2.}

Last night, I went over to my friend's house for our monthly game night. After we spent hours on charade, pictionary and etc., we decided to end the night with an easy simple game but with a fun little twist...

*The following words and letters $(C, Q, E)$ have been encrypted using the same set of Monoalphabetic substitution.

$(1)$
$$beginmatrix & C & Q & E & \ C & lym,lym & bcylg!,qpkc & qpkc,bcylg! & \ Q & qpkc,bcylg! & lym,lym & bcylg!,qpkc & \ E & bcylg!,qpkc & qpkc,bcylg! & lym,lym endmatrix$$

$(2)$
beginarray
hline
mathrmqplyicb = E&mathrmycpl = C&mathrmiqcpl = Q\
hline
mathrmisj = Q&mathrmsmiej = C&mathrmskjmiee = E\
hline
mathrmglpr = C&mathrmrpbgyl = E&mathrmrplb = Q\
hline
endarray

$$scriptsize*(use E)$$

After the game ended, I made a gravely stupid decision that eventually got me into a serious trouble.

$(1)$ What is the game and what is the addition to the rule?
$(2)$ What was my gravely stupid decision and what was the trouble I was in?

Hint:

Notice the pattern of the words on the same row and then $use E$ (literally and figuratively)

Trying to fit before Raichu:

It's a drinking rock/paper/scissors with C-Q-E being R-P-S, so the outcome is either drink!/pour or nil/nil.

The twist is, you probably used items you could find around as the playing items (instead of hands, as normal people would). That would explain the table beneath the scoring one:
poniard = S, act = P, knob = R, iron = R, clast = R, bodkin = S, apron = P, cutlass = S and bond = P.

Final solution

Words in each row are quite similar phonetically, although being different types of attack. Everywhere the E-word (scissors) includes both paper and rock as a sub-anagram. Crossing out the letters used in those sub-anagrams, we get:
p o n i a r d (-apron-iron) = D
c u t l a s s (-act-clast) = U
b o d k i n (-bond-knob) = I

Which resolves in DUI, common abbreviation for DrUnk drIving.
Which, ironically, is exactly the answer of Excited Raichu!

The game was

Rock, Paper, Scissors, I think

because

there's a 3x3 grid of outcomes. Whenever a letter intersects with itself, it's a tie, and C beats E, Q beats C, and E beats Q (or the other way around.) Not sure about the twist though.

Alright, now I'll make an attempt at the cipher.

"lym" is most likely tie. "qkpc" might be lose? "bcylg" could be... I'm not sure if there's a synonym for win with five letters. C, Q, and E are R, P, and S, in some combination. As @WAF pointed out in the comments, that's probably the order they're in, as the pattern "miee" wouldn't work for C or Q.

I think I have another breakthrough.

LYM converts to NI*, which is probably NIL. YCPL then converts to IR*N, which is... iron? QPKC is coming out to POUR, which makes sense given the context.

The cipher is now busted wide open, so

you used everyday items as the "pieces", as given the second chart... S can be poniard, bodkin or cutlass; R can be knob, iron, or clast, and P can be apron, act or bond.

All together:

You were playing a drinking game of Rock Paper Scissors, using random objects instead of your hands. The loser poured the winner a drink. However, after, you got into a lot of trouble when you were caught driving drunk (or actually crashed, while driving drunk.)