Brags. Beats. Battlestar Galactica.

I tried out some Rush 100PLO just now to mix it up a bit, and I ended up ~$900 in an hour. I must say, I don't usually do well at Rush, and I'll attempt to explain why by talking about the 100bb structure and how it differs greatly from deeper games.

I usually play the 100-250bb games, which, although they have antes, still play significantly deeper (I wrote a post somewhere explaining how the presence of antes restricts the amount you can raise when you pot it pre compared to no antes.) I also play a lot of HU, which starts at 100bb deep but quickly results in matches of 200bb+ effective stacks.

Changing the depth actually changes the game completely. I find the 100bb deep game to be somewhat incomplete, because it's too easy to get the stacks in by the turn. For example, let's say you open to pot pre and get a couple callers, the pot is probably already around 11bb. A bet and a call takes this to about 30bb, with probably 85bb effective stacks, which leads to a lot of automatic situations where both players are already committed, especially after one opponent bets again. Meanwhile, there is little behind for an opponent to leverage the other on the river if they call, so it usually results in an all-in confrontation. With 3-betting a lot being the norm, it's very easy to get stacks in with a single check raise on the flop, which is not that interesting because a lot of hands' equities run pretty closely on the flop and it becomes a simple mathematical decision (where the answer is usually all-in. It's also very easy to combat 3-betting because a 4-bet gets a significant portion of your stack in pre allowing you to shove the flop.

Compare this to a 250bb game, where a pot and a few callers leads to a 20bb stack. The SPR is much higher here and it will not longer be easy for opponents to just check/raise the turn all-in, given how much they need to risk. There is also still a significant amount left on the river if a player check/calls the flop and turn. In 3-bet pots, it's not as simple as c/r-ing the flop all-in. It's also pretty hard for anyone to 4-bet every AA and profit.

What are the main differences in play styles? 

Firstly, position is more important when deeper, as you get less opportunity to use your position when you have less big blinds to leverage on post-flop streets, as an opponent OOP has many more opportunities to get his stack in and disable your positional advantage. i think this was the main adjustment problem I was having, as I usually make somewhat speculative peels in position in the deep games hoping that my opponent will make huge RIO mistakes even with a stronger hand pre-flop. This just doesn't work very well when you're 100bb deep; floating light becomes tough as your opponent can easily bomb the turn and commit himself, or check-raise all-in when you bet. Raising flop also is hard to do because your opponent can simply 3-bet all-in.

Secondly, preflop hand selection matters a lot more. It still matters when you're deep, but it's very very important to not play too many hands in the 100bb game. Unlike deeper games, you are not setting up situations where you own your opponent a lot postflop on the turn and river; instead, you are setting up situations for the flop, where the battle will often take place. You are generally looking to flop something good and play from there, quite commonly playing for an all-in confrontation where you are on the better half of a flip (although, in loose-passive games you still get a lot of spots where people are check-calling you for multiple streets.) This means you can't afford to play the hands that leave you with weak draws postflop or otherwise you'll just be getting it in 40/60 too often because of a preflop mistake.

Here's an example hand from my rush session of how deep stacked play changes things:

Full Tilt Poker $0.50/$1 Pot Limit Omaha Hi - 6 players - View hand 1017885
DeucesCracked Poker Videos Hand History Converter

CO: $55.75
BTN: $182.25
SB: $100.00
BB: $211.80
UTG: $100.00
Hero (MP): $173.05

Pre Flop: ($1.50) Hero is MP with A 5 3 K
1 fold, Hero raises to $3.50, 3 folds, BB raises to $11, Hero calls $7.50

Flop: ($22.50) 4 T 5(2 players)
BB bets $22.50, Hero calls $22.50

Turn: ($67.50) 7(2 players)
BB checks, Hero bets $47.50, BB folds

Final Pot: $67.50
Hero wins $64.50
(Rake: $3.00)

I think this call would be bad if the stacks were shallower. Even though the hand is double-suited and has straight potential, the A35 actually fails to flop strong straight draws often (there are plenty of gutshot flops where we have enough equity to get it in vs AA** but aren't that happy), and the presence of an A in our hand actually leaves us in not so great positions on lots of flops (especially as we need every out we can get to make two pair). Also, it's not as if flopping a flush draw and then flipping vs AA** is a huge win for us, which is a result that will happen fairly often. However, being slightly deeper, you get more room to manoeuvre post, more implied odds on when you making a flush and more fold equity against overpairs on certain boards.

The flop call is actually fairly speculative even this deep (I wish I had been a touch deeper or had more nut outs, or he didn't bet full pot), but I figure his range for 3-betting from the BB is mostly big pairs and high cards. This means I can comfortably rep a lot of cards that change the board, such as a 6, 7 or 8 and he'll be check-folding a lot, fearful of stacking off with few outs against a straight. I also have 6 very good outs that are almost always clean, as well as possible two pair outs, in case I need them. If we were only 100bb deep, he could easily just get it in on a lot of turns and take the play away from me, nor would I really get the implied odds on my good cards.

The turn brought a 7 and I followed through with my plan. It's very hard for him to ship here, even if he had a flush draw, because it's hard to know how light your opponent is peeling that flop without history. This situation is also a prime example of why it's bad to 3-bet mostly high pairs this deep, because even on the drier boards like T45r, you could easily be facing a tough spot by the turn versus an opponent who can leverage position against your marginal hand.

Although both are viable games, I generally find 100bb deep PLO to become quite robotic in nature. There are a lot more automatic decisions and therefore less opportunity to use hand-reading and postflop skills. It's also much higher variance, with frequent of close all-ins where you are pushing relatively small edges. In the deeper games, you find much more situations where your opponents will make huge turn or river mistakes where your edge is much bigger.