OK, finally had some time to sit down and get in some quality play time with Pyramid Plunder. Most of my observations have already been made by others, but I think I have a couple insights which are original.
1) The music is really interesting, though it does get a tad repetitive given how long it takes to clear such large levels.
2) The sound effects are retro AND appropriate. Same for the graphics. Good job!
3) I love the run ability, and I like that you have to stop running to pick anything up. It might be worth making a minor tweak to try and nerf the use of the medium turbo speed to both run AND interact with stuff.
4) The level scrolling is too loose. I can get WAY too close to the edge of the screen before the level scrolls over. This makes it very difficult to know if it is safe to wander into off-screen territory. The mini-map helps, but if you're looking at the mini-map you're not looking at the screen.
5) I find the mini-map most useful to figure out where the enemies are when I get a power pellet and to figure out where the rest of the level is relative to me. It is not as useful in the moment when I'm trying to figure out what's off-screen immediately in the direction I'm headed, in part because that's a little too imminent for me to want to try to switch focus.
6 a) The levels are just too big. The ability to run helps, but when you're doing actual work, picking up pellets, nabbing baddies, and trying to actually grab the power-ups that float on-screen, you have to be walking, so you are inherently slow going about the real business of the game. Between how long it takes to clear the level and the enemy AI, the levels start to drag about 1/3 to 1/2 in. The Pac-man AI works well for small boards, but it gets quite lost on these larger levels
6 b) I like the IDEA of big levels, and I think there can be a place in the game for them, but they're likely to need a bit of reworking. Perhaps a more aggressive AI that is quite different from Pac-man, more off-screen wrap locales, and faster warps. Basically, if there's a way to speed up play on the larger levels, either by ensuring there's a steady stream of power-ups to speed up the characters or warps, wraps, and other shortcuts to zip around the level, then they'll become more interesting and more challenging. I do like some of your big map layouts, and I hope you don't scrap larger maps altogether so much as find a way to make them work a little better, perhaps intermixed with smaller, faster levels.
6 c) Maybe the larger maps could be challenge levels. Have a series of smaller (but still possibly bigger than a single screen, in some cases) maps and then have a huge map as a challenge map. Might be worth playing with the idea of more than 4 enemies, and even a second respawn base, on the bigger maps. That would also let you introduce more AI routines. It could be quite dangerous and cluster-f*ck-y, but it could also make for more opportunities to score big points taking down enemies with power pellets. Any changes like these, however, would probably require lots of extra play-testing, so that's a major drawback.
7) The combination of the late level scrolling and the fast movement power-up is almost as dangerous as it is useful. It is great fun as long as you're staying on your current screen, but as soon as you have to move to a new area and scroll the screen, it becomes quite dangerous, because of the small view distance and the high rate of speed. Might be nice to have the run button (as in the button that makes you run, not the Run button) slow you down when you have the speed power-up as a way to give you some finer control back.
Some of the enemies seem very reluctant to leave the enemy base/home. I had one game where one of the baddies spent almost the entire latter half of a level just wandering back and forth in the base and not popping out for me to either flee or kill.
9) Because the levels are so big, currently, it can take the ghosts of the enemies a really long-ass time to get back to the base to respawn.
10) The ghosts are adorable. I love their bouncy locomotion.
11) The little Indiana Jones jingle at the start screen is a cute homage, but it REALLY doesn't mesh well musically with the title theme that immediately follows it.
12) I think your engine is technically sound. Everything looks and sounds good, and everything plays pretty well, at least until the screen scrolls or until I've played half the level and am starting to get a little burned out on the level taking too long to finish.
13) Is there any chance you could/would implement a little bit of a control buffer? Let me see if I can explain what I mean. If I'm walking down a corridor to a T intersection, where I can go either left or right, if I don't push left or right I just stop and run in place. OK, that's cool. If I hit left or right a square early but don't hold it, I also stop. It might be nice if it buffered the last direction press for a few milliseconds/a full map square until it can actually perform the desired direction. That way you could just tap left or right as you get close to the intersection and if your timing isn't perfect you don't just run into the wall and stand there. I tend to prefer tapping the Dpad to holding the Dpad in these constant motion-type games, and if the directional presses aren't buffered just a little, it makes the tapping style of play a little harder vs the holding style, IMO. I realize this is kind of an esoteric complaint, but it was salient for me.
14) It was interesting to try and figure out what the power-ups do. Some of them are more valuable than others, but they do add a nice variety to the game.
I guess I'll post again if I have any other thoughts on the game. So far I'm pretty impressed. I do hope this title continues to mature nicely.