It is actually pretty rare to find a sequel or an update to any piece of software which is a complete re-write. Why re-invent the wheel? It is clear, however, that the Devs were really pushed for time on SH4 and some of the bugs left in SH3 are still in SH4. We are all hoping that the devs will be allowed to fix those bugs and the new ones.
The similarities are actually a major advantage for the modders. The modding forum here is full of newly released mods already!
|