This leave me in an interesting place. With the sudden vacuum of bugs I have been thinking of taking mine off the self just to throw into the arena. I have been playing with the Celestial Lions a lot lately and the CSM have been getting some good action, while the IG have been in the background since the Lions got up and going. I have not played a lot with my Tyranids since 3rd Edition, but I have thrown them around a couple times in the last year and have done alright with them. I am not planning on taking them to any tournaments or anything but just using them in our casual weekly games at the store.
Now as for as play style with them goes everyone in the area was very different. We had the Massive units of Warriors and Genestealers in one, Tons of MCs in another, Null Deployment, and an all shooty list. Back in the day I tended to go with large groups of gaunts with 2 medium sized Genestealer squads, Hive Tyrant with Guard, a Fex and Zoanthropes. Now a couple years ago I went ahead and picked up the new Hive Tyrant and 30 gargoyles as I thought I would start reworking my Nids... (I never got to it except for repainting most of the army).
Some tactics/strategies that I have used in the last year or 2 with good results are:
20 Devourer Gaunts in a Spore Pod
20+ Hormagaunts w/Adrenal Glands and Toxin sacs both normal deployment and outflanking (Hive Commander)
Dakka Fex in Spore
Naked Fexs just running
And the Crown Jewel is...
30 Gargolyes w/Adrenal Glands and Toxin Sacs backed up with a Catalyst Tervigon!
The large squad of Gargoyles not only give cover to the Monstrous Creatures behind them, they move fast enough for the units behind them to run, and with Feel No Pain from a Tervigon they seem to last most of the game. If my opponent focuses on the Gargoyles the Hormagaunts that are right behind or flanking them get closer unscathed as well as all the MCs. If they target the MCs and the Gaunts then the Gargoyles ruin their day as to many people underestimate the mass fire from the Gargoyles in combination with 2 attacks at WS3 Str4 (thanks to Adrenal Glands) at I5 (again thanks to Adrenal Glands) and because they are poison they get the re-roll wounds against T4 and lower. And with Str4 on the charge they can even glance most vehicles!
I know what you are thinking... "Glancing hits on 6s won't do anything!" and to be honest I don't care! If I can stop a vehicle from shooting and or moving I will be happy as it saves my bigger creatures from being shot and it makes the vehicles easier to hit. Most of the time if there are infantry inside a transport they will just stay inside as they 1) can't get out OR 2) don't want to take the risk (and high likelihood) of death. This helps save my smaller bugs.
I think I will continue this as some other time. Till then, Happy Wargaming!