Virtual On Marz
Marz is a departure for the series, leaving it's arcade roots for a more "free-roaming" feel. Virtual On: OM was good, even playing on the Saturn without the twinsticks. VOOT for the Dreamcast, was kind of weird with the control at first, but playable. VO Marz, however, just doesn't seem to have the magic that the series used.
I blame it on the game design in general. In the first two games, it was one-on-one mech fighting action. Then someone came up with the bright idea of having two-on-two action, which brings us to Virtual On 4 Force. They skipped the number three and the third game is labbeled four. Now, instead of having to deal with just one gigantic robot coming at you, there's two. To even things out you've got a buddy. Like most VO games, the arcade version barely existed and as far as I know, 4 didn't make it to the States.
VO Marz takes the gameplay (most of it, anyway) and turns it into a console game. Instead of just two-on-two arenas, either yourself or yourself and a partner take on several other Virtuaroids. The series does not seem suited for this style of gameplay. I would liken VO to Virtua Fighter, in a way, in that for every action, there seems to be a series of reactions, a set of balance, definitely a strategy. Basically, there's some depth to the one-on-one fights. Once there's a bunch of Virtuaroids flying around, suddenly this seems to disappear. Imagine if Virtua Fighter was turned into a Streets of Rage-style game. Would VF's mechanics hold up? Probably not. Look at Shenmue - this is how the game was adjusted.
The game system seems dumbed down as features such as different dash buttons and few moves are missing. The default control scheme consists of hitting buttons for jump, dash, attack and heavy attack. But wait, haven't there always been three weapons? Yeah, your letting the PS2 pick which one to fire for you. Other control options are available, using a couple of ways to mimic the original arcade sticks. The Dual Shock has two sticks, which seems logical enough to me. But, because the arcade's controllers were digital (on and off only), you can also use the d-pad plus the shape buttons to replicate the two sticks.
Virtual On Marz Official Site - It's pretty good, having lots of info on the background and the V.R.s in the game. Even though it's a Japanese site, there's an English version, so no translator is needed.